70 c10 wiper trouble

[dzbowtie]

the original wiper motor acted very weak. it was a 2 speed non- depressed motor, rectangular body, 3 prong. with some wd40 and a lil assistance from me, the wipers would move back and forth. there was no telling how long it had been since they moved, so i sprayed the transmission arm down really well. thinking the motor was weak from the years, i got a new one, same design and connected the original wires. however, this motor is acting the same way. when the power is on, and the wipers are turned on, they hardly budge if at all. if i pull on a wiper blade a little, then they start to move, but stop without my assistance. im about to get the truck on the road, and need to get this problem solved. could this be a bad transmission arm, or would a new motor have to power to move more than it does? could the wiring be bad? bad ground? im lost. thanks for any help.