The posting of the capacitor problems led me to accidently discover a bad solder joint which had killed my IC-751 display more than a year ago. THANK YOU!
Mod: IC-751: Put a little 12-vdc computer fan in the bottom of the 751 and this will eliminate all those heat-related problems with trimmers and caps getting too hot from the 8-v regulator sink. This one mod will could save a great deal of expensive repairs. It solved my overheated PLL trimmer distortion problem.
Mod: IC-751: I put 1/8th-inch mini-jacks in the rear panel connected to mic-in, AF out, and PTT, to allow easy connection to computer interface. The AF and PTT wire to the ACC jack. The mic is harder, requiring shielded line to the mic connector PCB. This also puts phantom power on the rear jack, allowing use of inexpensive computer headsets with electret boom mic and one earpiece.
Mod: IC-751: I installed the Piexx UX-14PX interface, and am very happy with it. It was $145, delivered very quickly. It provides BOTH CI-V AND RS-232 on the rear panel, without any additional external converter. It adds PTT and S-meter functions (and several other features) that the original ICOM part (UX-14) did not have.
Mod: Icom SM-6 microphone. I put a tiny switch in the side of the SM-6 base to kill the mic audio line while sending SSTV and other computer modes. With the rear panel jacks connected to the computer (with a simple homemade interface), and the switch on the mic, I don't have to (1) swap jacks, or (2) buy a WAY overpriced rig interface.