If you are losing the settings you are losing main power, otherwise the bug is in the radio. And unless the replacement has the same bug, the problem is in the harness or fusebox. Swap the fuse anyway - I've seen far too many that look OK that are broken internally.
I've only had one, not counting the harness replacment program, problem with my wiring. My cabin blower fan kept cutting out last spring. I found a half melted fuse and fuse holder. Ended up splicing a jumper and a separate fuse holder in the system to work around the problem.
