We sell the parts. If the pulley needs replaced, we rent the tools and offer technical support.
I couldn't agree more with Brain (OH) that the clutching alternator hub is more likely than the tensioner.
And, I might add, it's not always 'the cheap part', but the quality part.
As example, we recently had a customer send us a set of AMC PD cam bearings, sold by a well known vendor. The bearings were loose in a bag. Every bearing was beaten up and in my opinion, unusable. BUT THEY ARE CHEAP!
I'd rather spend money with someone who knows what to look for and what to avoid.
“The bitterness of poor quality remains long after the sweetness of low price is forgotten” – Benjamin Franklin