I believe these are the common HP design with solenoid coils driving two plungers that switch the pads in and out. If you have not overloaded the 10 dB section, then likely the problem is with some really tiny o'rings on the plunger shafts. Once the o'rings deteriorate, the action that moves the fingers that connect to the pads does not move enough and the section goes open when asked to switch it in...
The solution is to take it apart and replace the o'rings....If the pad is bad, it will have to be replaced also.
I can do this for you if needed (for some $)
Dan in Chandler, AZ
