The MTL lanes at the top of the game. I think the M and L lane wiring is backwards. When you go through the "M" lane, the "L" letter lights up (and visa versa). I looked under the playfield to switch the wires to the MLT lights, but they don't seem long enough to switch. Any other ideas?
All 3 lights are on the same board. Simply unscrew turn it 180 degrees and screw it back in.