One possible cause of CPU resets could be a low +5vdc. That's generated on the power supply board. Luckily the power supply voltage can be adjusted. Here's something to try to slightly increase the voltage to see if that helps or not with the resets.

With the game on, CPU board measure the HP1 connector with voltmeter set to measure volts dc. Red probe on pin 1, black probe on pin 4. Probably the probes can't touch the connector with it plugged in, so might have to get creative and look for something connected downstream of the actual connector on the CPU board. C25 & C42 are connected downstream according to schematic. Should measure about 5volts dc here. Record that original measured voltage.

Now with the game off, find a small phillips screwdriver and rotate VR2 on the power supply. Repeat the above test and verify that 5vdc measurement is slightly higher. If VR2 was turned the wrong way, it would decrease the voltage so need to verify that voltage increased. If it decreased, turn the other way and repeat the test above till the voltage is slightly higher than it was originally, say +0.5 volts.

Run the game and see if resets have decreased or stopped happening.