A friend has a 98 non super and the tensioner pulley was squeeking. Her brother bought a new pulley at Oreillys and put it on. The problem I now see is that the belt wants to ride off the edge of the pulley. It looks as if the pulley is not straight but at a very slight tilt. Is there a spacer behind the pulley or is the tensioner itself bad. I just put on a new belt for her because the old one got chewed on the edge that is hanging over the pulley edge. I know the belt is riding on the pulley wrong but need more input. I read that there is a spacer or washer that needs to be on there, but her brother doesn't know if he put it back on or not. Please help! Can i get this solved if the spacer/washer iss missing? What to do? his girl is really nice and I want to help her badly. Thanks.

It does sound as if a spacer/washer was left out. If the belt is hanging over the edge the tensioner pulley, and sitting square on all the others.
There may be a spacer that goes behind the tensioner arm, where it bolts to the engine.
You say the pulley looks crooked though? It may have a line-up pin that didn't get put into the right spot.
Take the belt back off and remove the pulley to see if it was installed correct.

does anyone have a picture of the tensioner pulley assembly when taken apart? I need to see what the spacer/washer looks like. Thanks