Ford Repair: Noise / Squel / Belt Tensioner?, ford contour, workshop type

Question
QUESTION: My daughter's 97 Ford Contour (2.0L w/air) had a squeal a few months ago. It seemed to go away. Today it came back with a vengeance (loud squeal and noise only when engine is running) and her car stalled out twice on the road. I was able to nurse it home. Poking around with the engine stopped, I found the serpentine belt very very loose. I couldn't find any of the engine components loose (A/C, Generator, Idler, PS) so I took the idler off and the belt off. The belt has a few cracks, but it doesn't look horrible. I reached down, though, and I am able to move the tensioner up and down with my hand.

I don't know how the tensioner is supposed to work. Is it supposed to move like that? Is there some mechanism that engages once the engine is on to make the tensioner take up the slack against the belt?

Is it possible the belt is just worn to the point that the tensioner is ineffective now?

The bolt in the tensioner doesn't seem to be loose at all, but, I can move the tensioner up and down if I grasp it in my hand and tug on it up and down.

I'm trying to decide if I should just put on a new belt, or if I have a more serious problem such as the tensioner.

Can you help?
Thanks a lot-
Bill

ANSWER: bill change the tensioner and the belt , very common problem , it shouldnt move like that

---------- FOLLOW-UP ----------

QUESTION: Thank you. Can I ask a follow up? Can a novice (such as myself) replace this? I have regular workshop type tools - nothing specialized, though. If I were to get the part from a dealership parts store, is this something that a normal guy can do with normal tools, or, is this something that should be done at the shop? Also, would the car run well enough for me to get it to the shop - say 5 or 10 city driving miles?

Thanks so far. What a blessing you are.

Answer
i think you can do it not too hard , you might have to do it from the top and from the bottom there are only 3 bolts that hold it in , u would need a 10mm wrench , and a 13 , if i recall that is all after taking tire off  and if u want u can drive 5 mins or 10 to shop u should be fine