Replacing Ador motor

[Ballerina Bird]

Has anyone done this? If so, I would really appreciate directions. The company owner is always very helpful, but since it is the weekend he may not be available and I need to fix this asap. If you have replaced your motor, I would be very grateful for advice written for someone with mininal diy skills -- I get easily confused by this stuff and am low on experience with tools and sprockets. Thanks!