the 100,000 light turns on when the X player 100,000 relay is powered (where X = 1st - 4th), so the first thing to see is whether the appropriate relay is powered for the player you are having trouble with.
if you mean that when manually stepping the 10,000's score reel from 9 -> 0 the player 100,000 relay powers and stays powered, but when the game does it the 100,000 relay doesn't power or stay powered, then the only difference is how fast the game is doing it and the mechanical shock/vibration caused by the solenoid plunger slamming into the coil stop.
if the problem is just on one player, then check the E.O.S. switch on the 10,000 reel unit for that player.