CCWR
CCWR did indeed suffer from overheating. It was originally designed using Germanium technology, requiring significant cooling. In the early 60s this was upgraded to Silicon devices. The LRU that suffered most was the Control Indicator. Once modified, its cooling fans were removed, which some thought too drastic. I cannot speak for civilian airlines, but MoD still used Germanium in at least 1990; probably later given IFS's 1997 report.
A major difficulty arises if an aircraft comes along whose cooling convention isn't compatible with Germanium. The failure rate increases but that is not the fault of either the CCWR or the aircraft.