Beginner attempting restoration of Mark III

I just discovered this forum and I am glad to be here. FYI: The last piece of Dynaco equipment I owned was a ST-70 that I paid $15 for. After dusting it and rebiasing its EL34s I used it to drive a pair of Quad 57s for several years. That was (obviously) a while back. More recently I picked up a pair of Mark IIIs that were rescued from the attic of an old Victorian... and I am considering trying to get them going again. The amps are complete, but are very dirty. The 6an8 boards are so badly coated with grime that the resistor color bands are not visible. What do you recommend for safely cleaning 40 year old Dynaco PCBs of grime and flux? I see lots of flux that undoubtedly dates back to the original assembly.
...j

I will give Windex and isopropyl a try... I'd like to get the old flux off too. I have begun pulling the amps apart and they are not too pretty inside. Mismatched tubes, ugly solid wiring with melted insulation at the solder joints, and it looks like the chokes have been hot--wax/goo transferred onto the bottom cover. Is there a way to evaluate the power and output transformers using basic test gear? I wouldn't want to invest any more into these amps until I know if the rarer bits are any good. FYI: One amp powered up and runs okay. The second powered up and ran with a sort of "clipping" distortion--until the fuse blew after 2-3 minutes. I measured the quad cap on that one and bypassed the two bad sections, that amp is running on the bench now too thanks to your "sticky" guidelines on this forum. Thanks for that.
...j