as I understand it, this condition seems to be a common "wear with use" related item...w/ SEC/ 300CE/ E320 Coupe's

I exercise extreme caution to avoid the sawing effect (and now it is habit) when retrieving the belt from the butler...

fyi- a plastic gear going out in the butler is also a common malady (due to wear and tear over time)....there's a (non OEM/OE) metal gear that can be retro fitted to strengthen this weaker point in the system

good luck
-fad