We repair vintage tractor magnetos and have had the same problem. Some aftermarket points are not usable out of the box. The contact surfaces sometimes are coated with a lacquer, shellac or even oxides that need to come off and the surfaces do not line up without some bending. Sometimes we need to do some filing to get the clearance correct. Unless the rubbing block or
contact surfaces are worn away we recondition them. If there is a reddish copper coloured tinge when you polish the contacts that means that the tungsten or platinum contact surface has worn away and new points are needed. This is very rare in our experience. Most service literature from back in the day describes using a fine sharpening stone or fine diamond file like an EZE LAP. We also use a Cratex stick. It resembles an eraser with abrasive in it and comes in various shapes and sizes and grit sizes. Red is medium and slate is fine. Order direct from Cratex. These will leave almost a mirror finish that will stay clean in jig time.