Starter problems

I just bought this thing i took it to a mechanic because of grinding when tring to start he replaced the flywheel had 3 broken teeth i brought it home parked it try to start it and started grinding again i called him he came and got it and said he shimmed the starter i got home today tried to start it and was still grinding now all it is doing is spinning i have a feeling the flywheel broke again but is there any ideas as to what can be causing this it has a new starter and flywheel and still grinds any help would be very much appreciated.....