EM noob guess, assuming that the initial light or first bonus earned is wrong - stepper motor that keeps track of the bonus is not fully resetting to correct position.

The game should start with no bonus lamps lit. There are a couple of YouTube videos that show the gameplay.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball.htm
http://www.PinWiki.com - The new place for pinball repair info

I'd start with Frax' suggestion.
--
Chris Hibler - CARGPB #31
http://www.Team-EM.com
http://webpages.charter.net/chibler/Pinball/index.htm
http://www.PinWiki.com - The Place to go for Pinball Repair Info

You can see another view of game play on my youtube page:

http://www.youtube.com/user/SirSteveFury?blend=1&ob=0

The game starts with no bonus lit at all. Getting A or B or C or D or E lights corresponding star rollovers, and the lit star rollovers add bonus. Also dropping a 1976 or 1776 target, or exiting through the out lanes also advances bonus.

I have completely rebuilt the Spirit of 76, the 4 player version of your game. The bonus unit was also rebuilt and the biggest problem was the old grease had solidified causing the ratchet assemblies to stick. This was a problem with all the stepper units.

This is the location of the bonus stepper unit:

Playfield-Components.jpg

Since I've recently gone through my SO76, maybe I can help you with this. If you need a schematic and other documentation then PM me with your email.

Is your 1st ball served with no bonus lit at all, or is the 1000 bonus already lit, so your 1st earned bonus advances to 2000?

Check this out first as others have stated. Might not be resetting all the way because of old grease or weak springs or may be off by one rivet/space and may have to be adjusted accordingly loosing the screws on the disc to position properly.

Ken

+1 Bonus unit is my first guess also. Look at it and make sure it is set to 0 position.

At the end of each ball the bonus unit should count down to zero and award points.

If your game previously worked fine and the disk screws are still tight, and the ratchet stops the contacts center one to another then it's not likely a disk position adjustment problem.

First thing I'd do is manually operate the subtract solenoid until the ratchet reaches its end and check the zero position leaf switch stacks and make sure they are operating properly.

Then I would also start a game with the bonus unit not fully subtracted and watch it reset itself as the subtract solenoid pulses, particularly where it stops and make sure each of those leaf switches are working properly.

I'm not at my game at the moment but I'll snap some photos tomorrow if I possibly can.

Guessing by the schematic I would say probably no rivet.

bunus-unit.jpg

You should be able to manually advance the bonus unit up to... say the 5000 position for example, then manually step it all the way down past the 1000, and the last step is when the 1000 is out.

Scrub this video to 2:15

Does your bonus subtract all the way until the 1000 goes out or does it remain lit on the last position?

The maximum possible bonus on this machine is 1500.

If you manually operate the subtract bonus solenoid until the ratchet is at its end, and that is where the zero position switches are actuated- and the 1000 bonus light remains lit, it sounds like the disk is off by 1 rivet position.

I'd maximize the bonus unit to 1500, loosen the screws scuring the disk and move it back so the board says 15000 not 16000. If the bonus unit is working properly it is not possible for it to display 16000.
When you win more than 15000 the add soloenoid continues to pulse for each bonus win, but the ratchet physically won't advance any further because it either hits a stop or a tooth is stamped out of the ratchet, preventing advancement.

According to the schematic, the disk only operates the board's indicator lights and nothing else.

+1 upvote. My stepper that displayed balls remaining on my Top Card would do the same thing, but in reverse. You wouldn't see a light indicating ball 1. Ball 2 would show ball 1, and when you got to "ball 4" if you drained it your game was over. Was pretty easy to fix once I figured out it wasn't a wiring thing....first and only EM I've owned so far.