Is there a switch in the shooter lane on this game ? It sounds like you have a switch that is not registering but I don’t remember if it has a shooter lane switch , it has been a while since I owned an episode one .

I'm not very familiar with the gameplay for SWE1. Is light saber battle a multiball? If so, is it the only multiball during which the issue presents itself?

Here's a link to the manual, in case you don't have one:
https://www.ipdb.org/files/4458/Williams_1999_Star_Wars_Episode_I_Manual.pdf

Page 1-15 describes how to perform the switch test. Remove the balls and see if any of the trough opto switches are still registering.

Try cleaning the opto switches in the trough. You can also try cleaning the coil assembly for the trough.

It's the only multi ball where you have to manually plunge more than one ball, and it's endless, so it's always trying to serve up another ball.

In regular multiball you've locked two and it serves up the last one, and if I recall correctly there is no ball save on multiball, so it's never going to try again.

There's a switch in the shooter lane where the ball sits that's supposed to tell the game that there's a ball there (switch #18 on page 2-42 & 2-43 of that manual). Go into switch test in the diagnostics menu and manually engage that switch using a ball (don't use your finger, it's squishier than a pinball and can activate a switch much more effectively than a ball). In switch test, it should indicate that switch is being activated on the screen when you put a ball there, as well as any other switches currently being activated (eg., the opto switches in the ball trough if there are balls in there).

Alternatively, you can go into the solenoid test described on page 1-15. Also on that page, it states that "In order to operate the tests that use the +50v or +20v circuits, pull the interlock switch button out. The interlock switch is located on a bracket in the coin door opening". Set the solenoid test to "repeat mode" and cycle to solenoid #09 for the trough eject. Have the playfield in it's normal resting position with all the balls in there. See if you can get a glimpse of the ball behavior when this test is running (specifically, the first ball being ejected while there would be one ball already in play on the playfield, simulating the conditions of starting this multiball). See if the trough eject mechanism is causing the other balls in the trough to roll back up a little bit. If the last ball in line is pushed back up to activate the opto switch behind it, the game can think there are more balls in the trough than there are and prematurely eject another ball.

However, if this were the problem, I would think that it would occur any time a ball was served.

Sorry I wasn't implying it was intended behavior as it's definitely not. I was just thinking through the logic. At this point in the game its thinking there is no ball in the shooter lane, and there are some in the trough. The game has 4 balls, but you can only play three during the Jedi Battle, but the 4th can be locked in a saucer.

I'm thinking somethings up with the trough opto sensors, as I think if it was the shooter lane switch it'd do it all the time. Either way we need a report on the switch test.

I have the game for a few years now. During the Darth Maul battle, a new ball will be kicked into the shooter lane when a ball you are playing drains. You can shoot as many balls into play as you like. After each plunge a new ball will kick into the shooter lane until you slay Maul, or Maul slays you
Also there are call outs for a ball sitting in the shooter lane unplunged. Anakin will say “Shoot the ball and use your flippers!” If you are hearing that call out, I would guess the shooter lane switch is good. Sounds like optos in the trough to me. At no time is there ever three balls stacked in the lane.