The Machine
This Stern Guardians of the Galaxy came in with a seized Groot jaw lock mechanism, with a $80 driver board that had paid the price for it.
What Happened
The Groot jaw mechanism uses two alignment rods and a motor with gearbox to open and close the jaw for ball locks. Both rods are retained by two e-clips, and on this machine, one of the upper e-clips had broken and allowed the rod to fall out of position. With only one rod in place, the jaw lost alignment, rotated some and eventually bound completely.
This is arguably a weak point in the design — when the jaw seizes anywhere below the upper position, there is nothing to protect the motor from stalling under load. The motor draws continuous current trying to drive a mechanism that can’t move, the result was a cratered motor driver board, thankfully not taking anything else out on the game like lamp boards or a node board (which is unfortunately quite common).
Repair
One new e-clip, many expletives trying to get said upper e-clip installed successfully, and one new 520-6996-00 motor driver board, the game was good to go.
With the mechanism rebuilt and the driver board replaced, the Groot jaw operates correctly again. I wish these motor drivers were more robust, they fail often and when they do, they can send 48v down the 5v rail used for the serial communications and nuke lamp boards or node boards.