Looking for a bit of advice. I have started to have a humming/drone noise coming from the auxiliary belt area of my 1.9 tdi 130 AVF. Car feels sluggish at the moment too. It can be heard on tick over with a ticking noise i think coming from the alternator. The belt looks like it's jumping about a bit on the tensioner. Also on full lock I'm getting a screech. I imaging it may be one of the pulleys. Any ideas how to find the culprit.