Dodge Brothers Club

A few months ago my clutch started slipping, when warm, if I tried to start from a stop on a steep incline. I followed the manual procedure: pushed pedal in, dribbled in solvent, rotated lots, finished with neats foot oil. Car still slips when warm — again, when on a steep incline. I am wondering if oil could be entering from the transmission. I am not TOO full, but perhaps have a touch more than the manual suggests. It seems to me oil could easily leak forward to clutch area. Originally, the drain hole beneath the clutch was plugged, and when I cleared it, a lot of oil drained out. But I have kept that hole clear now for a while.

I am inclined to clean with the clutch with kerosene this time, and see if that helps give me better performance. I would skip the neats foot oil. Opinions? Thanks very much in advance.