Hi, I am in the process of installing new contact points on a '74 DT175A. I have purchased 3 sets of points for this specific model and none of them fit. The rubbing block on the points will not touch the lobe on the flywheel, hence, I assuming, incorrect points. (no bump, no intermittent spark) The engine is original, numbers match, and the flywheel numbers are correct for this engine. I have elongated the attaching hole, filed points metal for clearance and still no rub on lobe. Obviously, I haven't gotten to the timing or points gap, yet. Any help earns eternal gratitude. Desperate! Many Thanks!