I’m sure that Bietrume’s meaning is absolutely trustworthy:
Of course, we all would like to find out what’s the initial reason for the twisting of the belt - if you change part nr. 338 and leave the old belt it couldn’t be verified if the initial reason was 338, because the belt might fail due to the above quoted reason.
If you replace 338 and freewheel it’s the same situation.
To find out if the culprit is really the 338 part you’ll need to replace the belt - and keep the old 338 part to see if the twisting happens again.
But doing that means also to damage a new belt (very probably), that’s an ugly double windmill (translated with different words: “to be caught between devil and blue sea” or “catch-22”).
I’m really sorry but I can’t help to decide…
However, one thing should be mentioned: The bolt 379 must not be overtightened, but it must be secured with bolt adhesive.
I mean the overtightening is the initial reason for the bending of the “washer section” (the narrow piece with the bigger diameter) of 338.