Mellotronists

>    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?

You may want to look at:

http://www.kleonard.com/mellotron/vt0206/work.htm

"Typical Korb Mods", #3.  Even though it "shouldn't" cause noise 
issues, it does in some cases (however it's crackling, usually, not 
necessarily a hum).

If that's not it, see if there's anything applicable here:

http://www.mellotron.com/tech.htm

I have an SMS-4 in #805, and I performed a low noise mod outlined on 
that page.  Hum gone.

ALSO...Radio reception.  First, uncoil the coily ground wire going 
from the harness to the frame---that's a great antenna.  You can also 
reorient the machine or move it to a different location.  If that 
doesn't work, you'll wind up filling your machine with grounded 
aluminum foil and/or covering it with a grounded aluminum jacket (ask 
Lee R. all about that...it worked, but in order to solve his problem 
permanently, he picked up his machine and moved to Hawaii away from 
the radio towers!  ;-) ).

...kl...
M400 #805 - unhummed
M400 #1037 - uncoiled

** Ken Leonard - Web Table of Contents:  http://www.kleonard.com
** Get Outdoors New England:  http://www.GONewEngland.org