tensioner pulley adjustment

[jb1016]

Hey guys, I'm getting a rattle out of my serp belt tensioner. I can see the source of the rattle -- as the arm pivots back and forth with the pulley, it clack-clack-clacks against the base on the left side. I know that's a terrible description; maybe I'll try posting a video later.

Has anybody else had this happen? The tensioner doesn't appear to be adjustable at all. Is there any fix short of taking a grinder to it for some clearance? Thanks in advance.

Oh, and by the way the tensioner is less than a year old, as is the belt. The rattle started about the time I put in a new alternator, maybe a month ago.