Quad Esl 2905 reliability issues?


I have owned a pair of Quad 2905 for six years problem-free. These are my favorites amongst the high end speakers I have owned so far. But lately one of the panel start to buzz and pop 30 minutes into my listening session. Does it mean that I have panel failure? I am puzzled because I am sure I did not over-drive the speaker.
mvp100
Mvp, I am not an expert on Quads but I have read that the panels can arc or short even if they are not abused. It seems to be a fairly common problem with them.

Maybe someone more knowledgeable can help you out.
Panel would be expensive. Try checking replacing the input bipolar lytic and the small 0.1uf cap somewhere midway between input and the panels. Sorry I forgot. Been too long. That fixed my 989.
The thing is one of the speakers is working fine but the other one seems to be faulty. I could still play my music if I just ignore the soft buzz and pops but will it get worse and affect all the other working panels.
Should I replace all the panels of both speakers or just the faulty ones if I don't want sound quality to be compromised .
The reading was about 30. The speakers are in a windowless room with air-con set on timer. What are the signs of high humidity affecting the panels?