06-10-2011, 06:15 PM
For a starter, I'd try to measure just how much current is going through the B+ using an old-fangled ammeter. Anything over 50-75 m.a. wouold be suspect. Suba P.M. speaker and see if the audio is clear. I assume you are meauring from B- to point in question, or however the schematic you have says how to do it.