Hi,
I had a IC-751 once which was a kind of problem child. I had to open it up a couple of times and most of the time it were dried out electrolytic capacitors. Below you will find a couple of pdfs with some more info about just this transceiver. I have been writing about these common problems before but the original file is lost. The pdf as described below was a great help finding problems.
- 751a_pll
- IC-751 A
- IC-751 and IC-751A Service. This is the famous troubleshooting site
- ic-751
- IC-751_service_manual
- IC-751A_User_manual
- icomprom
- ServiceMan751A
- UX14
- UX14_install