The double arrow inside the dashed box labeled "I Relay Disc" represents a small wiper on the I relay that gets rotated as the relay advances. The wiper connects different points on the contact board beneath it. The I relay has 10 positions so this pattern is repeated twice on the contact board that controls the lights. Chances are that the wiper that controls the arrow lights isn't making reliable contact with all of the positions on the contact board.

You may be able to manually advance the I relay and see the arrows on the playfield advance. That would help you identify which contacts aren't reliable.

Note that there are two wipers and two contact boards so check the wire colors to identify which board controls the lights.

/Mark

Have you already checked the I relay wipers? Are they clean and tensioned? You might also check the I relay jones plugs. They usually have their own jones plugs so they can be removed from the game for servicing.

I thought all the scoring was working properly? Now it sounds like neither the arrows nor the scoring is working consistently.

Have a close look at the two small wipers on either side of the I relay. As they advance they should always land in the center of the copper pads on the contact board. It sounds like your wipers may not be. Also check the boards for signs of wear, burning or pitting.

I respectfully disagree. If it's intermittent there's still work to do but with few exceptions it can be made reliable.