belt tensioner

I have a 98 3.1l malibu and the belt slipped last night. This morning I was able to get the car home and put the belt back on, but once I loosened the tensioner I am having a problem tightening it again. I thought I had it once but when I started it up the belt started to squeel after about 3 or 4 seconds. Turned it back off to check out what went wrong and it looks correct, but there is the squeel and a little smoke that looks to be coming from the tensioner. Does anyone have any ideas what I am doing incorrect?

Have you checked the condition (with belt off) of the idler pulley on the tensioner? Look for wobble or binding. Likewise, check the alternator, PS pump, A/C compressor and water pump.

Thanks for the help.... i took the belt back off and found the idler pulley was bad.