I'm wondering what's the right tension on the alternator belt, car runs fine just noticed a little squeak when I step on the gas.. Opened the hood and I see that the belt has a little play, just wondering what's the right tension and how to do it the right way.

 

5mm to 10 mm deflection midway between alt pulley and crank pully. Belt is adjusted by tightening the 10mm bolt on the alt.

 

YouTube video on a 940....

https://m.youtube.com/watch?v=QRSYYgNIqUc

 

Make sure that the three rubber bushings holding the alternator are in good shape. With time they start to wear causing you alternator to be out of alignment.