I guess you could try placing a straight edge across pulley faces from the hub pulley and see if they all align. Inspect all of the pulley bolts and any protruding center hub for evenness, possibly a pulley mounted with a tilt. Next would be to check the pulleys themselves with a straight edge to make sure they are true.

Last thing that comes to mind is replace that serp belt, its got a lot of cracking, and if worn in by your bad tensioner before, it is likely skewed now on a good set up and not traveling true under load.

Good luck

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)

Sure, it needs to be replaced. Had gotten one online that was The actual MB part, but the part number was wrong and it was 20mm too short,,,, went to AZ to get a continental belt, and it’s some subpar variant.

I’ll have a new quality 2120 belt soon. Hopefully continental contitech is still legit.

I have to think that I tightened the bolt too much which damaged it.

I also still don’t really know why the shock rubber shifted so much, like a washer’s worth…

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)