One of the first things you have to do when you get an original Gottlieb System 80 game is deal with their on-board NiCad battery pack, if it has not already been addressed. Gottlieb installed these batteries on the actual MPU board itself and like on other games, it’s a common cause of serious problems with the game. The batteries begin to leak after awhile, releasing electrolytes that corrode the MPU board and the components on it. This can happen even if you don’t see any obvious leaks. The batteries need to be replaced. There are a few options you have to do this: a remote battery pack (3 AA batteries along with a blocking diode to keep them from being charged if they’re not rechargeable batteries), a 2032 lithium coin cell, or my favorite, a 5.5v 1.5F memory capacitor. The memory cap will last the longest and will not destroy any components on the board. It will keep a charge for at least a month or more without power. Here’s a video of me adding this fix to a Gottlieb System 80B MPU