Much has been written about the original RAM board, HERE is a good example
This is my only Icom rig at the moment, and has been owned by me since "nearly new" around 1990. This has a splendid receiver, and I have installed CW filters and the internal switch-mode PSU. Other IC-751A owners have complained about the performance of the radio with the internal PSU installed, but I have never experienced any issues with this, to date.
A problem with this radio for a number of years has been the famous Bad Cap problem. Another entry on my "To Do" list!
(If you find a broken link when looking up the "Bad Cap" problem, look out for Icom Knowledge Base article number 5B9F593A21 Icom often shuffle the pages on their web sites! I have a local copy here.
Most recently I have replaced the Icom memory unit with the PieXX unit as I felt that the original lithium battery must have been on borrowed time. More on this issue later.
Much has been written about the original RAM board, HERE is a good example