[EricH]

Originally Posted by waialua359

my guess is a window motor or possibly FP with the right ratio setup. It looks like a 50ish tooth sprocket for maybe a 5 to 1 ratio. Our ratio is a little higher with the window motor, which moves our arm with no strain on the motor. When we had a 4 to 1, torquewise was fine, but the speed was just a little too quick and jerky.

If it's a true Beach'Bot arm, FP, two-stage reduction. You'd probably be right for the upper stage.