Leave slack in the backbox looms
The backbox wiring is poorly tied down and too short, so folding the backbox for a move tugs on the board connectors and cracks their solder. Thin wires can also break inside their insulation and may need replacing. Add slack and support before moving the game.
Systems
Source: Repairing Bally 6803 Pinball Games from 1985 to 1989, Clay Harrell (pinrepair.com)