I go through Clays guides systematically, SI is the last game I worked on. These are generally the first things I do on these early Ballys
* rebuild rectifier board, check and replace fuses and fuse clips as needed, repin connectors, add specific mods to improve reliability. Check all voltages for spec.
* replace filter cap on SDB board, repin connectors, add specific mods to improve reliability, check display and +5VDC logic for spec and AC ripple.
* cut off and replace NiCad battery and replace with memory capacitor, NVRAM, or offboard battery holder.