Fixite7, you probably should post you question separately from this one for the sake of confusion.
I'll risk taking some ire with a short answer.

Some vacuum wiper motors have a "kicker" that can age and crack.
One sweep then stops. Doesn't reverse direction.
Post your question with year truck and Trico wiper motor number if you know it.

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."