Check the gears are aligned properly. There are known issues with the ac/dc cannon motor. Call stern if you don't see anything out of alignment. They will send you another one.

With mine it was hitting the ramp. Adjusted the ramp and works great again.

Also check the cable coming from the cannon is not getting caught . It also needs enough slack to have room to pivot . Sometimes the cable is pulled too far down under the playfield which doesn't leave enough on top .

Day one I sanded out a little from the ramp. Works great and would never notice.

My canon is jerky and need to rock machine to get canon to move.
My wires from canon to under playfield seems to grasp the rubber on bumper (near exit lane)
I have pulled the wires through but has made canon worse. I am thinking it can be motor as well.
I dont want to pee around with a $10k machine but looks like I might have too.
Also seen something on the forum saying SAND DOWN THE BRUSHES ON MOTOR. I will be trying that first as looks simple.
Will let you know.

whoops nevermind