Help: Crane machine controls stopped working!

[danguyf]

My 11 year old son, Xander, is a claw machine enthusiast, to put it lightly.  He started a dog walking business just to make money to use playing claw machines, because his mother was complaining that he was squandering his allowance.  He watches videos on YouTube reviewing different makes and models of claw machines and strategies for successfully retrieving prizes.  He won a small toy claw machine at the fair and has taken it apart multiple times to fix it.  Together, we have built a small claw machine out of LEGO MindStorms. So, of course, the only thing he wanted for Christmas is a claw machine.

To surprise him, I bought a used "Action Claw" machine (with "AC-1 Rev A" main board).   He loved it.  Unfortunately, the controls stopped working last month.

Expected behavior:
* user inserts money
* first button (back arrow) lights up
* user presses first button, releasing it when the claw is in place along the first axis
* second button (right arrow) lights up
* user presses first button, releasing it when the claw is in place along the second axis
* claw drops
* claw raises
* claw returns to the prize slot and opens

Current behavior:
* user inserts money
* nothing happens
* if the first button is pressed, a loud click issues from within the cabinet

I have made a short video illustrating the issue:

I am not as electronically inclined as I would like to be, so I have no idea where to start.  If anyone can give me suggestions or point me in the right direction I would be very appreciative.