The seat is probably wallered out too which can make it impossible to adjust. Mumbles showed me a trick using an end mill to resurface the seat by taking a few thousandths off of the face of it to square it up a bit. It seemed to help quite a bit 🙂 .
For the needle, I chuck it in a drill and use a file to take it down to where the groove is gone while keeping the taper angle the same.
