stop pushing it hard. You may break something that way.. A small tap with a toe should have it spinning.
For most treadles oil is enough. make sure you oil all the points where. metal moves on metal. both axles of the treadle plate, the connections to the pittman arm, The axle for the powered wheel. Leve the belt off the heed until you get it figured it out. One some models there are cone nuts at the treadle plate. If Igor wrenched on them, they could be too tight.