I think the most common mistake when dealing with the alternator belt is forgetting to loosten the tensioner pulley bolt. This is the bolt that goes through the bearing of the tensioner pulley. It also acts as a lock to prevent the tensioner from moving. If you don't loosten it, you stand a good chance of goobering things up pretty good.
The tensioning screw on my 94 was all galled up and bent when I bought it. The entire bracket is broken and missing on my 92 because the previous owner didn't know to loosten the locking bolt on the tensioner puller.
It sounds to me like this describes the problem you are having.
I spent a great deal of effort repairing the tensioner on my 94. When I was done, I lubricated the tensioner screw with some extra-heavy grease. This made a big difference. Before, the whole assembly was always stiff. Now, the assembly moves very freely. ...unless the tensioner pulley bolt is tightened.
