I don't believe the home and marks switches are part of the standard switch matrix.

Give this a shot, with the cannon parked at home, looses the 4 screws that hold it to the plate nut, then turn the gun CCW until the right edge of the cannons ball entry aligns with the right edge of the ball guide rail then re-tighten the screws.

Do you have some play in your home switch that will make it park a little further CW, so you can readjust it a little further CCW after it parks?

This may be a side effect of having a very tight home switch adjustment. If the home switch is adjusted to close to the top of stroke, it's own inertial can cause it to drive past the point where the home switch is closed and on power up if the cannon isn't at home it will cycle, the game doesnt care if the home switch stays closed, only that it closed. This is normal a non-issue unless the cannon is so tightly adjusted that it happens every time, this will cause the cannon to cycle every time the game is going to load the cannon since a home check is made prior to the game firing the VUK that feeds the cannon.

I don't think this is the issue either but you should be able to test this easy enough without replacing it; all you have to do is remove the 3 pin coil connector (violet wires) under the playfield and measure the resistance between the two connection points while the canon rotates. The only difficult part is these are male pins, but it should still be fairly easy to do. If I was going to check this I would use a 3 pin female connector so I wouldn't have to hold the probes.

I got nothing