Mellotronists

Hi everyone-
   I found a problem with my M400 I hadn't noticed
before.  I'm getting ready to tear it down for bearing
replacment & headblock cable replacement, so this may
be a good time for other fixes.  There is some hum
present all the time in the audio output.  It varies
with the volume control.  Probably need some power
supply caps changed, which I will check.  Motor noise
creeps in at a very low level, too.  
   Here is the main issue.  The hum increases on
tracks A and C, and is lower on B.  It also does this
when manually moving the headblock without the track
selector linkage engaged to the pin (left of
headblock).  Slight movement of the headblock cable
doesn't affect this hum process.  I haven't removed
the headblock yet, but I bet the problem is related. 
Is there a sliding ground/chassis contact gone bad?

   Thanks
    -Bruce Daily
    M400 #1221

PS- Happy birthday Mr. Wakeman!!




       
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