timing chain rattle after crank pulley replacement

[physics junkie]

1996 Nissan Avenir Salut X (came with an SR20de). My automatic station wagon crankshaft pulley outer ring was starting to wobble so my mechanic decided to replace it with one from a 1992(I'm not sure of the year) Nissan Bluebird ARX. Also, the car would squeal when you turned on the AC below 40km/hr or until it got warmed up. I am on a small island in the West Indies so parts are hard to come by...

The mechanic used a breaker bar to get the bolt off and tried to remove the pulley but it was stuck. The next day he came back with a pulley removal tool and removed the pulley. When I start the car now there is a very loud rattling sound that is coming from the timing chain.

One opinion that I've gotten is that trying to remove the pulley without the proper tool caused the timing chain cover to break and start hitting the chain. I'm not sure if this is feasible seeing as how the pulley wasn't actually pryed off but removed with the tool.

My mechanic does not seem very experienced and I am doubtful whether he knew how to install the pulley properly. What are the other possibilities? What should I check or try next?