Theoman. Check the plastic disks on the top of the main filter caps. If they can push down flat, most likely the caps are good. What's happening is the old heatshrink wrap is continuing to shrink and pulls on the disk curving it. No harm done by that, but it fools 99% of us non tech's unless you understand that they do get warm.
On the Main amp board 2 of the parts just off the input are reversed on the board, vs. the schematic. I asked when I found it on mine and was told by MTF it was ok either way. I think it was C1 and C3 on one channel and C2 & C4 on the other, but I'll check my thread. (It's vetted on PAGE #2 in the last pair of pics and explanation). http://audiokarma.org/forums/index.php?threads/another-939-rebuild-thread.494501/ Had a lot of fun with this one. I still haven't reveneered the case but I do have the veneer for the case. And it continues to pull Baltimore and D.C. Stations in with that Dental Pick on the one side of the 300ohm antenna terminals. I don't have the heart to put a regular T-Dipole on it, it sounds so damned good!
If you're familiar with the 1010 there are more than a couple boards that are the same # on the 939. So you can use the 1010 parts lists for those boards if you don't have the 939's or to verify the parts in case the lists for the 939 got lost.
Very nice 939 , when l first got mine l wasn't that impressed with it but after a rebuild it was a very different sounding receiver and is now my favourite and pairs very well with any speakers l can throw at it.