[cws5]

My excellent MG Head Mark II, which I bought used and have had now for four years, has developed a crackling and intermittent volume drop in the left channel. I've scoured the forums and elsewhere, and have learned of the following possible causes: (1) bad tube, (2) corrosion on tube pins, (3) corrosion in tube sockets, (4) bad resistor. I've successfully eliminated (1) and (2). Here's a description of the intermittent symptoms and a question. Symptoms: (5) left channel volume drops slowly to zero while listening, but if power toggled then left channel volume restored; (6) when powered down, left channel loudly crackles. Question: does (5) or (6) suggest the likelihood of (4) over (3) or vice versa or neither?

I welcome the help of those with experience of such problems before I take the Head to the electronics repairman.