grand prix R bonus always steps down. i can manually trigger it up to rack some points on playfield lights, but then when you try to play a game, it just decresases them 5000 pts at a time each time a bonus target is hit. when you reset a game, the left starts out at 5k, and the right is zero, meaning no bonus lights are lit.

-if i manually rack up right bonus points to get 15 or 20k lit up, flick some left bonus targets...it will decrease the right bonus points lights on the playfield, while adding the left side bonus lights on the playfield.

i know this prolly sounds very confusing, trust me (it's even worse actually being here working on it). ive tried explaining this the best i could, but basically it seems the right bonus unit is starting off 1 step too low. it needs to be one step higher in order to illuminate the 5k bonus light on the playfield, just as the left bonus unit is doing. once that is figured, i think we can move forward as to why it steps down the right bonus when it shouldn't.

**also, the change relay isn't working, not sure it's tied to this issue. shoot the ball out of the lane and one of the first targets it can potentially hit on the top of playfield "advance right bonus when lit" or "advance left bonus when lit". hitting these targets should alternate to the other. meaning hit the one that's lit for left bonus, it should switch the light to the right target. this is not occuring. not sure it's related to the above mentioned issue, but wanted to leave all info i could**

checked this, didnt have those color combos on any of my switches on the right bonus relay. i have a blue/black wire switch with a yellow/blue wire. or i have a blue/orange wire with a yellow wire.
regardless we made progress, the blue/black with yellow/blue wire had 1 strand of wire jumping them. fixed that and now we're not subtracting the right bonus. here's where it's at now.

1-on a game reset, the right unit doesn't zero and start fresh at 5000, stays where ever the last game ended. middle of a game, turn off or unplug and turn back on, game over is illuminated. close outhole switch and left bonus unit counts down, push credit button and it does reset cycle and shoots ball out, left bonus is at 5000 and right bonus is wherever it was in previous game.

2-whatever side the arrow is lit up to score, after ball drains it racks those points and steps down the unit, shoots ball to lane, returns unit to 5000, and then steps up the opposite side unit.

as far as the change relay...
1-what and where is the 00-90 unit? many of my stickers are gone and i couldn't find that unit labeled in the instruction manual.

2-closing the change relay manually with my finger DOES alternate the lights on the top of playfield.

did some more tampering. left side seems to be working ok...i think. overall right now it seems like the left bonus unit isn't resetting. it thinks it's resetting and firing the step up coil as it should, which is why when the left side drains the left bonus unit down, it fires up 1 click to the 5k mark. but, since the right side bonus unit isn't resetting, it doesn't know that and it's till firing up to what should be the 5k mark. i checked the blue/orange and green wire switch on scm 2D, and that seems to be making good connection. is there somewhere down the line after this that fires the reset coil on the right bonus unit?

the b1-26-800 coil on right bonus unit should be firing for a reset when the ball drains, but it is not. it is working because when it steps down and scores the bonus for the right side, i see the coil firing as the bonus light steps down. but when it drains a ball and is scoring the left bonus, the right side should reset to zero and then step up to 5k when the ball shoots to lane, this isn't happening.

00-90 unit just needed the switch adjusted. working properly and moving the change relay and alternating the light. right bonus unit seems to be fixed too, had some incorrect wire labeling on the schematic and machine it seems