I am about to replace my serpentine belt on a 1995 S500 w140 with the 190 engine.

I think I have located the tension adjuster, but after searching the forum all the ones mentioned seem to have a bolt in the center.

Mine has what looks like the end of a torx screwdriver sticking out of the center of the pulley. I found the posts on how to replace the belt.

How do I loosen this type of tensioner/adjuster and what should I look for to determine if it is worn and should be replaced?

Also how do I retension it after installing the new poly-v belt?

Mike