To cut to the chase, old maggies often have one major flaw, and that is how their wire voice coils got attached to their mylar diaphragms. The material used can break down in one of two ways causing two different possible problems over time. For this reason I suggest people buy new or used MMG's rather than older SMGa's or MG-I's or II's simply because you cannot assume what their condition will be like, especially regardless of what the owner says about them.
If however you already own older speakers and you know they are in good shape and are willing to run the risks then you can mod them. What I am leery about is buying older ones unseen. (note that I said seen and not heard. NEVER judge by hearing them, as it won't tell you anything. They must be looked at.) The following explains what I know of the problems of older models, and what I am willing to do if your speaker arrives with some slight delamination. If it needs major work they should be sent back to magnepan for complete overhaul.
Q: Will mine delam?
A: Possibly, but not certainly. Maggies may go quick (4-5 years), or you may get lucky and last a good 10 to 12 years. In fact it may not happen at all. This depends mostly on where you live and secondly how you treat them. Cold humid dampness kills them and if sea air plays any part in that then it's 10 times as bad. So the worst areas are cold climates near the ocean
Q: Does any model have a higher incidence of failure?
A: No, other than original models from the 70's are most suspect simply because they are oldest. (in fact they may be on their second or third relam already)
Q: How long does it take to happen?
A: That's impossible to be exact about. Some get a slow death, going green and getting tacky but never quite reaching a state where the wires come off while others literally spill their guts in a year or two. If they age by turning red however they will not delam but you can expect tweeter failure at some point.
Q: Is there a cause?
A: The 3M product does not hold the wires down, it just keeps them in place long enough for the coat of milloxane, essentially a pvc type glue, to cure and form a "second skin" over the wires. While direct sunlight is bad for milloxane, humidity is the real problem with cold humid air being worse and cold salt air being the real killer. Every pair I have come across that spent time within 20 miles of a northern ocean delaminated, and they do so in a quicker period of time. Units that stay in dry areas, especially the midwest to the southwest, tend to not delaminate but they can dry rot. Consistently warm and humid areas like Florida seem the ideal location. They don't go red but never quite delam either.
Q: What happens?
A: One of 2 things. Those that are in humid areas turn green. Apparently long term exposure to cold moisture makes milloxane get funky and break down, which given that water is it's solvent is not surprising. (but interaction with the 3M may be suspect in this as well) Over time that greening will get tacky, then sticky, then gummy, then really shot. At any point from the sticky period on the wires may start coming off. Those in warmer dry areas actually oxidize instead and turn red. I have never seen a mid/bass wire failure or delam in a red maggie, but tweeter wire failure is not only common, it should be expected to happen eventually. Normal, unmolested play usually will extend their lives, but once you ship them and/or upgrade them and make them play at a higher level it tends to force the issue and the already weakened wire will break. When this happens they will break still stuck on and you can't even see where the problem is because the gap is so fine. If your tweeter isn't playing check for continuity with a tester at the solder blobs and if you get none you can bet you have a break. You'll then have to order a repair kit from Magnepan.
Q: They wear in 2 different ways?
A: Yes. Those that turn green suffer mid/bass delamination (but their tweeters rarely if ever delam and they don't oxidize and fail) and those that turn red don't suffer from delam but the tweeters will dry rot at fail at some point. (what's the quote, can't win for losing?) I have also seen speakers in both conditions, with tops that are red and dry and bottoms that are green and gummy. (I call this stoplight syndrome) I suspect the cause of this is them being kept in a basement and/or on a cement floor where the tops are up in the drier, warmer air in the room and the bottoms are near the constantly cold, damp floor.
Q: What's the best defense?
A: Keep them as warm as possible and avoid moisture and the sun. Packing them away in the box in a closet is also sure death. If you must store them, leave them open with air able to get at both sides. (if they lean against a wall stick a shim between them to keep them apart slightly)
Q: Will I know I have wires coming off? Will I hear it?
A: In virtually ALL cases, no. Using listening as a guide to delamination is a sure way to get into trouble. Visual inspection is the only reliable method. Banana peel for instance only makes audible "burrs" in the very early stages when it is still somewhat close to the mylar, and even then it rarely does it. Once they come off a few inches they no longer interact with the mylar so from that point they almost can't make a wrong sound. Mid panel delamination, which happens at more advanced stages (maggies "rot" from the ends and until air can get in under there the middle usually stays OK) can happen and when it does it is usually a real noise maker. Since it is still held at both ends the wire stays in contact with the mylar and it will rattle and buzz. (like a kazoo) You will find that certain things in certain pieces of music causes the buzz, and will do so every time. Tweeter wires by comparison will sound shrill when off. It's a God awful sound and there's no mistaking it. If you hear tweeter shrill stop playing them immediately and get them fixed. The more you let them vibrate like that the greater your chance of fatigue and breakage.
Q: Can I mail you my speakers to fix my wires?
A: No. I only offer the service to people getting stand mods done, and even then I will not correct massive panel failures. It is not enjoyable work and it's Magnepans fault not mine. However I will fix them for customers because knowing the problem as I do I am sure pairs will always be arriving which need the work and the owner will have had no idea any such problem existed. In my desire to get them back the best functioning maggies I can I will do the work for them.
What will happen is when you are sending me your maggies for stand work, I will ask you to do a general inspection by running your hand along the rear fabric paying special attention to the tops and bottom. If massive failure is happening you will feel the wires lifted up against the fabric. (if you are willing to remove a sock and look, so much the better) If you do feel delam you will have to remove the socks for an inspection. If the wires are not more than 35% off I will take them and do the work. Failure greater than that should be sent back to Magnepan for service. (35% means the wires are not lifted more than apx. a third the distance from their end to the panels middle)
My work means I will repair them using the method I outlined in the Audio Asylum Planar section. This involves cleaning the old glue residue away with acetone and then adhering the wires back down with DAP. This method so far has proven reliable and permanent unlike Magnepans method. My own pair have been fixed now for 3 years with no failure of my work or new failures. However, there is no guarantee wires I do not treat may still come off in the near or long term future as again this is Magnepans problem. (please read our user agreement) I have started using a method I call "proof" coating which treats the remaining gummy wires, which I believe works. I will do this for those maggies which need it but I cannot guarantee it will prevent future gumminess or failure in those areas. However to date it has worked and held up on every model it has been applied to.