This machine normally will be in tilt mode at power on. The backbox lights should be on, playfield lights off, game over light on, coin entrance lights on. The ball should not eject unless resetting the machine. Upon resetting, the playfield lights will light. The AX relay is the heart of the reset sequence and is quite sensitive to proper adjustment. Ensure that it is correctly working before messing with the score motor or anything else. You can also check the coin detect. If they stick, it will cycle endlessly. Does the score reset at all?
The switch you point out is one of a few slam switches designed to prevent the cabinet from being picked up and dropped. If this switch is opened at all during a game, the game ends. The tilt switches are located below the left flipper button. There is a pendulum and a ball switch.
Cleaning, tightening and adjusting every relay is an excellent approach. Once a relay is adjusted correctly, it won't give you any problems for many, many games. This game has several latch relays in it. They successively close with each ball lighting up more of the add bonus targets and rollovers. There is also the KS relay which handles the spinning target and bagatelle lights and bonuses.