Hammond M102 Problem with volume control...HELP?!

[dillweed4]

I got a hammond M102 this summer from oxford... got it for £300. Most of it works, there are just a few things that I am having problems with....</p>

 The most irritating problem is the fact that when I play it, the volume changes, it is usually quieter than it should be, then it will suddenly go loud for a little bit, then quiet again. I hear it may be something to do with dust and the expression pedal, but I am not sure. It also has this sort of crackly sound that goes with it.</p>

 Any help solving this problem would be greatly appreciated.....</p>

Thanks, Dillweed4 </p>

[sfp1954]

Sound like the electrolytic capacitors in the power amp need to be replaced. They only have a design lifetime of 15 years max.
They aren't holding a charge, then they charge up a bit, then they collapse. So you lose and gain power as they struggle to keep up.
You can try taking the cover off the swell pedal free air capacitor (the square metal tower with the spring attached to it) and blowing it out, but I think a power amp rebuild is what you need. I recently bought an M3 that was very soft for the first several minutes and the all of sudden cut into full volume with episodes of scratchiness. Rebuilding the AO-29 cleaned it all up.
See:

http://www.stefanv.com/electronics/h..._overhaul.html

I also replace the three .047 coupling capacitors in addition to the main overhaul. The amp is now quiet as a whisper and has lots of power.

You can try cleaning all the tubes and tube sockets with deoxit but I believe your caps are the main issue.