When I have a Fuse blowing issue, it turned out to be a open/close switch where both sides were closed. Power was being drawn to both sides, that cause too much draw so fuse would blow. I would check the circuits that are activated when the motor is in the position that blows the fuse.
Since you were working on the score reels I would check the relays in the back box first.
The outhole relay and game relay are two examples in this curcuit.
outhole relay (resized).png