Help with Martin Logan Quests.

I have an original pair of ML Quests that have served me well for several years. I seem to be having problems with the panels sounding weak or losing volume. They still play but at a much reduced volume compared to the subs. I have substituted other components and think the problem is with the speakers.

Has anyone experienced problems with the electronics or panels that might fit this description?

If these need to be serviced, does anyone know who can do the work and maybe do parts upgrades in the process?

Thanks for your help.
First, check directly with MartinLogan--they are on the web if there is no dealer near you. Second, are the panels clean and tight? Third, sometimes the panels need to be replaced after "several years" of use. Fourth, the Quests are now at least 3 generations old--maybe it's time for new 'Logans (rather than spending money on repairs or upgrades). ;>)
Vacuum the panels. When I sent you the message I was in a hurry so there are grammatical errors that I did not correct. Here is the clarification. A second procedure is to vacuum out the electronics. Don't touch anything inside if you don't know how to dissipate the charge. And make sure everything has been disconnected for 24 hrs before you do anything including vacuum.
I spoke to a tech support at ML a few months ago regarding this same issue. He told me that there is a "life expectancy" for their ESL panels that range from 8-10 years depending on usage. After that, the above mentioned simptoms are normal. I own a pair of Sequel IIs and the cost of the panel replacements are $549 +SH. This comes with a ML 3 or 5 year warranty. The replacing procedure is pretty simple and your speakers will sound as wonderful as the first day you brought them home. My panels have not reached that point yet, but may soon. Till then, I came up with a smaller and cheaper (less that $10) but not the most "correct way" of reducing the bass due to room geometry. My Preamp does not have any bass or treble controls, so an inline resistor did the trick for me. I can give you more details about that if you're interested. Best of luck and happy listening.

Thanks for the suggestions. The problem seems intermittent. They are working fine today. These were purchased around 93, so they may need new panels. I'll vacuum first.

The Audio Control equalizer has done the trick for the bass. It is an inexpensive but effective cure. I've thought about using a resister, but the room problems are too severe.
All of the advice above is good. Do vacuum the panels regularly, but honestly--it's time for new panels. M-L has made a number of improvements for their panels, and you will benefit from these as well as the fact that yours are probably near the end of their life expectancy--particularly if you live in a humid area which lowers the life expectancy.
Shahens, since I am bi-amped and use the speakers passive crossover, the amps are still seeing full bandwidth. An active crossover takes some load off each amp but I can't do that with these speakers. You mentioned installing an inline resistor and that is something I've thought about on the input to each amp to remove some of the frequencies that will be remove by the speaker crossover. Did you install the resistors before or after the amp?

Thanks, and happy holidays to everyone.
Rives, you are probably correct to encourage me to replace the panels. I'm not ready to spend the money for a new pair. New panels would sound better anyway, but what about circuit upgrades. Should I have someone replace circuit components with improved parts? I've done this with box speakers before and had good results.

Both times I have had this problem, it went away after a few hours. When it happened on Monday, we had just painted part of the house (away from the speakers), and had opened the house to clear the smell. We live in South Texas and humidity is always a problem. On top of that it rained some that afternoon. We closed the house and turned the AC on around 6 pm and the problem was gone by 10 pm.

Thanks for the help.
I would call Jim Powers at Martin Logan. Tell him the problems and the results--particularly the last story. While, I can share my experience with my Martin Logans (and a few friends), he hears hundreds of experiences and works to resolve them. He is a great resource and can likely tell you if it's the panels or possibly something else. My guess is that it's the panels and the combination of high humidity--but would be interested in what Jim tells you. He can also tell you what circuit updates were made and if they make sense for you. Your speakers may not have the auto off/on which could be a significant upgrade being in a high humidity area--they increase panel life quite a bit. Mine didn't have this either, but I just created a manual method that I used to accomplish the same thing.
It sounds to me like you have a major humidity problem. Before replacing anything get a voltmeter and a spl meter. If you have a noise generator or a test CD find the 2.83 volt output level at the output terminals of your amp (do this on a "dry" day). Then measure the speaker output with a spl meter at that level. On a wet day repeat the procedure. If the panel outputs are dramatically different you have a major humidity issue.
Iam glad you posted this my problem on quest is on speaker
it will play and then suddenly the sound would go down from
top to bottom and will hear only a little sound but its
tricky because my plinius one channel also went down
this is the side that is connected to the speaker that
got the problem,other side is ok. my guest maybe its the
panel although i doubt it, i think maybe some parts inside.
good luck,
I would like to thank everyone for their comments.

It has been a week since the problem occured, and the speakers are working fine. I think it was a humidity problem as described in an earlier post. I still think I need to begin considering new panels, but can probably squeeze a little more life out of these.

Best regards.
I own a pair of original ml quest also. About a year ago one of the speaker started malfunctioning (no sound). Haven't done anything to them (too busy). But I did speak with the ML rep and he indicated it may be the power supply. He suggested swapping the boards with the good speaker to narrow down the problem. Also, like everyone saids that the panel needs to be rebuilt. good luck