I recently r/r'd the water pump on my 1993 300se and after reassembly I have been unable to adjust the tension on my serpentine belt. I can adjust the rod all the way in or out and I get no movement on my tensioner pulley. I noticed the adjusting rod can be put back on the tensioner more than one way. I do not know if I reassembled this incorrectly or not. I have removed and installed it in as many ways that will allow and still no pulley adjustment. The pulley rests hard up against the water pump pulley. Could the shock absorber that is attatched to it be a problem as it appears to be an opposing spring force? Or has the tensioner just gone bad for no apparent reason? I find it hard to believe that the tensioner quit as the local Mercedes dealer says he rarely ever sells one.