I repaired the constant ON the NEUTRAL LIGHT by replacing the PNP transistor BD370. The instrument cluster had to be dismantled to access the circuit board. I desoldered the OEM transistor, cleaned the three mounting points, and soldered the new one in place. Before reassembling the entire front end, I plugged in the instrument cluster for a successful test. The neutral light is on when in neutral. When I shifted it into first gear, the neutral light went out, and the same happened with the other gears. When the neutral light stays on, regardless of which gear is engaged, it is a serious safety issue. In any gear, the bike can start without pulling in the clutch. Sure, you can use the gear indicator, but mistakes can happen. If this happens to your K you'll have to dig deep to locate dead stock. When you solder, keep your iron no higher than 600 degrees f to reduced overheating the new transistor. Use a magnifying glass. (K75s 87 Original Owner)