There is plenty of length in the cables to tip the IF chassis up. Pull the filter and BFO shafts out of the way, tip the chassis up and stuff something under the end - I use a piece of 2x4.
Hang a voltmeter on the AGC line on TB102 and watch it as you rotate the chassis up, just in case the problem is in the wiring harness / plugs. I had one where P112 was full of crud.
Thanks for the good replies and N2BC!!!!!!!! There were at least 5 green lights that went off in my head..........."Why didn't I think of that?
"
It's a heat problem for sure.
Fans will just blow dust and dirt into the chassis. Look inside a computer and you'll know what I means.
Fred