Hi everyone, My friend's 1988 M3 makes a grinding noise when you shift from 1st to second and downshift from 3rd to 2nd. Mechanic told him it was his second gear synchros that were bad and it would cost $650 for parts and labor. Car drives smoothly otherwise, does this problem sound like a big deal? does he need a new tranny? (I don't think so). Thanks for any input.