2003 Ford Explorer, EB, Rear Window Wiper

2003 Ford Explorer, EB, Rear Window Wiper hasn't worked for over a year.
Dealer says the motor needs replacing.
It could be that the motor contacts (brushes?)
simply need cleaning, although, I have no detailed service info to guide me.
Anyone know what is involved to repair? Easy or difficult?
I have no experience accessing components inside a door or panel, so not sure how much effort is involved.
TIA for any pointers.
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