A guy just put in my motor now my belt ride the edge of the groove. The guy that put it in for me says it wont go back any further and I dont want to just whack it with a hammer. Should I just whack with a hammer? Rubber mallet?

suggestions please.

 

What year is your car? What year is the engine? Are you sure they have the correct length hub on it - length varies by year?

Is it possible the rubber ring in the damper is damaged and the pulley has moved relative to the hub?

Generally not a good idea to hit the damper with anything.