66 mustang wiper motor question

So I got a 2 speed wiper motor, tested it prior to install and everything seemed good. Once in, it seem like the thing doesn't have enough torque to get it going. I still have my instrument panel out and I have to turn the switch to high and tug on the wiper arm. Once the motor starts, it works but only on high. It stops on low and won't restart afterwards. Initially, I was thinking the arms may have been stuck, but no luck.

Any one got any ideas?

Is it possible to install a single stage wiper and still use a 2 stage wiper switch?

Thanks guys

Initial tests before the install seemed to go well. my first one was bad. I will double check the connections this week and get back to ya. any idea about hooking a single stage up to a two stage switch?