Rear Wiper Motor

I have a 2001 Montana. I am wondering if anyone in Ontario has had to replace this motor and what is involved to do it. I assume I have to remove the door liner to get at it. If this is the case how hard is it to put it back on?
What is happening is that the wiper will only go in one direction when I turn it on. The only way it will return is if I manually swing it back. Kind of hard to do on the highway.
Does anyone have ideas for troubleshooting this before I replace it?
Does anyone know where I can buy one if needed without going to the dealer and paying through the nose?
Thanks, any help is appreciated.

I have a 98 Montana and have a bad rear wiper motor, My wife ran it when we had a bike rack on the rear lift gate. I had to remove the door trim to get to the motor, it's not difficult mine is attached by plastic push clips (there is a special tool made to pull these) I did not use the tool and now I have to replace the clips. After pullung the panel loose at the bottom the panel slid over the metal window frame on the bottom and was clipped to the pillars and top of the window frame. Then I had to pull the trim from the rubber alignment stops on the door jambs on each side. MAKE SURE IT IS NOT TOO COLD if you have to do this out doors the panel will crack or break. Once the trim was off it is easy to get to the motor. My motor has a striped worm gear and is inop. I had to take the motor off to get a look at the gear. to do this I had to take off the wiper arm. To do that I lifted the cover at the base of the arm and removed the nut holding the arm to the shaft then there is a plate with a gasket that if I remember correctly unscrews from the shaft ( it's been a while since I've done this), I then un-bolted the motor from the door frame & unpluged the wire harness. That's all there is to it.
Be careful putting the trim back on it can be a little hard to line up the push clips.

Did mine too. Very easy. About a 45 minute job. Worst part is taking the interior panel off to get at it.

Steve