Check your PS pump for missing bolts where it bolts to the bracket as they can vibrate loose and fall out ( ask me how I know). They are not easy to see from above so you can feel around with your finger searching for a hole minus a bolt(s) or look from below with strong light. I believe there a 4-5 and one is really obscure. If they loosen, the pump will cock slightly out of line under load and vibrate and squeal like a banche plus you get little if any assist when turnng the wheel. Also, if all the mounting bolts aren't there or are loose, you will not be able to tighten the belt with the tensioner no matter how much force you apply.