i think of the 7 or 8 of the TNF's that i repaired recently half of them had a bad amp. Either an LA4460 or 4461. I think one uses one and the other the other- but i don't remember which was which.... Easy enough to check in the schems though.
IIRC, i had one that had a bad socket on the sound eprom as well, and a few with bad pots.