Auxiliary Belts - Squeal - Tensioner & More

[cadman2k]

In January, noticed a Battery warning light with a bit of a squeal, just after starting the car.
As a precaution had the Aux Belt replaced. Since then no issues at all , until yesterday.
Have encountered the same thing again with squeal and battery warning light, noticed revs had increased on tickover also to 1K instead of the 800 that it normally runs at.
Obvious the belt was slipping again. Should I have had Tensioner changed at the same time?
After a minute this stopped and then all went back to normal, no squeals no battery warning light.

Suspect now it could be that the belt is not tight enough or has stretched.
Maybe the tensioner is sticking (although suspect they should have checked that prior to putting a belt on) or could it be a worn Pulley or maybe the Alternator.
Looking for thoughts! Engine is 2.0TDI 140.

No warning lights today (when i did the inspection)

After inspecting today did notice one part moving rapidly back and forth on tickover (is this the tensioner? and is this normal.
Have uploaded a bit of a Video at this link (its the part shown to the left of the alternator on this video, was taken from the drivers side looking in to engine bay)

http://yfrog.us/4zrmov0107z


Can someone verify this looks normal .?

Thanks in advance

 

[stuwbafc]

i think the part you refer to as moving back and forth is the clutch pulley mine went a few months back but i never had any lights on the dash or rev problems just very loud screaming from the belt...
not sure if its much help tho ...hope you get it sorted

 

[cadman2k]

Belts

So should it move back and forth or has it gone?

 

[stuwbafc]

it should move if we are talking about the same part.....

 

[cadman2k]

belt noise

Thanks, would appreciate if anyone has any thoughts