I've been working on a 1973 Gottlieb King Pin for awhile and I have everything working except one small problem. This game has two pop bumpers that can either be lit for 1000 points or unlit for 100 points. About 80% of the time, when the pop bumpers are unlit (and should score 100 points) the game scores 1100 points. When the bumpers are lit everything works fine, it's just when they are unlit, there is a problem. It appears that when the ball hits an unlit pop bumper, the 100s score reel increments by one like it should, but something is sometimes triggering the 1000s score reel to also increment by one.
Does anybody have any ideas as to why this is happening? I've cleaned all the score reels and score reel relays. I have also taken apart and cleaned the "Left / Right Pop Bumper" on the otherside of the playfield and that didn't affect anything. I've cleaned just about all the switches and relays and this problem still persists. Any suggestions would be greatly appreciated!