I talked to moultrie, they weren't much help.
There'll be a set screw holding the spinner plate to the motor shaft, either a real small allen screw or a phillips head. Take the spinner plate off, and that will expose two very small (generally phillips) screws that hold the motor to the housing. Take those screws out, and the motor will fall away. Some of the motors plug into the timer with spade connections, but most of them you'll have to cut the wire. No big deal, carry out a couple barrel crimp connectors, strip 1/8 or so of the sheathing off the wires, tuck them into the crimp connector, and give them a squeeze.
Oh, and when you take the two very small, very easy to lose screws off to drop the motor out, hold on to them. Most replacement motors won't come with new screws, so you'll have to reuse them. I like to put a little loc-tite on those screws when I put a new motor on, what with the vibration they're subjected to.
You can get the barrel connectors and a small thing of loc-tite at Auto-Zone or similar for cheap.
Oh, and what everyone else said about buying a new motor, just about any sporting goods place will have them.