From #1441 then UE10 is almost certainly faulty.
#1439 seems to show UE9 is OK, but as you say could possibly still be not long for this world and Colin is getting quite expert at replacing chips now, after all he has had plenty of practice, more than me in the last few years
It would be interesting to know the result with only UE10 replaced, just to confirm the debug process if nothing else.