Which end are you speaking of? The end that the bobtach pivots or the back where it attaches to the machine? If its where the bobtach attaches to, you can replace the pins, there should be a bushing sleeve inside the bobtach that you need to replace too if its excessively worn. You can't really install oversize pins as the holes don't wear evenly, they go oval shaped and an oversize pin will not fit this new hole. It should be sleeved (not too easy to remove but can be done).