Thanks for the replies and suggestions.
This morning I tried it again and by putting a lot of pressure on the shaft, I moved it out a couple of inches and then couldn't get it back in. With the help of a friend pushing in on the slide and me putting pressure on the shaft, we got it back in.
I took the suggestion to contact support at Power Gears and got basic info and links and confirmation that the motor was probably bad (which I already knew).
I replied and asked again what I could check and how hard it should be to turn the shaft with a socket on the end.
I then got this reply:
" if something is defective or bound up inside the motor gearbox, it can keep you from moving it easily or at all."
I went and took out the two bolts connecting the shafts on each side of the motor. I put a pipe wrench on the motor and it was all I could do to turn the motor with the "brake" off. Couldn't turn it at all with the brake on as it should be.
I put a socket on the shaft and gently turned it and the slide started moving. Went to the other side and it moved easily as well. Going to make a coupler tomorrow to connect the two shafts together and then see if the goes in and out without any problems.
If that works (I think it will), I'll get a new motor and put it back together.
Lesson learned: If a motor goes bad and you can't manually get the slide in or out, check first to see if the motor/gearbox is locked up.
My first post and with members help/suggestions, I'm happy and relieved.