[Collins] Got that sizzle

[pentoad at aol.com]

After flawless operation for the past six years, my KWM-2A is showing 
disturbing signs...  When I try to tune, as I get closer to resonance, 
I start to get a disturbing sizzle (the frying bacon sound) from the 
transciever.  The set is rack-mounted, so I really haven't been able to 
get a feel fo the source.  I've checked all connections through the 
30L-1, 312B-4, and out to the antenna...everything's right.  
Suggestions on places to focus my troubleshooting as I pull the 
transceiver out of the rack will be welcome.
Thanks and 73,
Ed N0AUB