True you/your dad could have caused something to go bad, but after such a short time away from the shop its worth a shot for you to at least ask or confront them about it. Whats the worst they could say is no and youd just get it fixed like you are planning. Who knows they may cut the price back alittle seeing as you just had it there.

 

Replace the pilot bearing if you haven't already. They're cheap and easy but will make racket in there. The FRPP one of those is best as well, and the Lethal retainer.

 

Find a new shop.

Dave