I know everyone gets tired of these questions but, I`ve done everything on this site to fix my squeaky belt.
I`ve had the bike 4 weeks tomorrow. It had 2231 mls on it.   It now has 3230 mls on it. After riding it for 3 days, the belt started chirping. I read this forum and checked my belt, and could not do the 90 degree test. I couldn`t even do a 45 degree. The bike came from the dealer this way. The man I bought it from is a good friend, so I know how the bike has been treated, ect.
I loosened the belt until I could do the 90 degree thing, lined the back wheel back up and still chirping. Loosened it up some more and it stopped, but if I got down on it very hard, the belt would slip. I tightened it back up to the 90, cleaned the belt really good and notice that the rear pulley had the slightest bit of play in it. Is this normal?
Someone suggest what I need to try. Thanks in advance all.

There are rubber cushions in the rear pulley to absorb the shock/stress.  It should have same play.

Belt slip???????      It's a toothed belt.  It has to be extremely loose to "jump" the teeth.