Middleby Conveyor won't work

Getting an ERR message on the timer on my lower conveyor on my PS 360. Oven is 12-13 years old. Middleby said that it could be a loose wire on the speed controller. Opened it up and all wires are tight. Anyone have any ideas? In the past when conveyor motors have died the oven did not show this error message.

More that likely either dust build up between the speed sensor pickup and the spinning magnet, or a motor brush is worn out. Can you post a picture of the motor?