Quoted from Md2020:
I purchased this game DOA and have torn it completely apart for cleaning. The CPU board was sent out for service and to have the transistors replaced as well as the barbecue capable resistors. I know that the coin mech's are not part of the switch matrix, so I suspect I could test directly at the board to determine if its at the CPU or not
Yes, coin mechs ARE a part of the switch matrix. Look at your switch matrix table again in the manual. All the coin mechanics switches are in column 1. Yes, you can test directly at the board, to rule out a problem there. Even though the board was sent out for service, and you would hope that it was tested and worked 100%, it could have also been damaged in transit or during reinstall. Plus this will help rule out any playfield wiring issues (If everything works direct tested, but then reconnecting pf fails, you would have suspect playfield wiring or switches)
No need to pull and reseat any chips until you find it necessary. For now just press them down securely in socket (to resolve any possible chip creep)
Where you mentioned not knowing what do look for in switch test, just get the switch matrix chart from the manual, put the game in the switch test. It helps to remove all the balls and use one to activate ball triggered switches, and just see that every switch reports back the correct number on the display.