1) you want a minimum of 15" of vacuum at idle. 17" is better, 21" is optimum.
2) disconnect the wiper linkage and test/check them for binding.
The wipers should move easily by hand.
Since you had the motor rebuilt by wiperman you shouldn't have to do this next step.
My wiper motor was completely inop. I poured about a tablespoon of 10w30 motor oil down in vacuum intake port of the motor and sloshed it around to ensure it coated as much of the interior as possible. Hooked it up and it's been working great since.
I figure the oil helps to seal the internal bellows.
I would imagine wiperman lubed the motor up when he rebuilt it so you may check w/him before you add oil.
Good luck
Dave
