This video helped me immensely. That 1862 I picked up recently would hard start, but seem to run ok after warm up (It is/was running slower than my 1811). I drained the fuel overnight (it was a slow drip). pulled the seat, fender pan, fuel tank. Found the fuel shut-offs clogged up. Cleaned up the years of crud, repainted the foot pads while they were off. Fuel flow nice and full now. Starting better. Real test will happen after the foot pads are back on. (Paint drying)
While I had the tank out I tested the fuel sensor. It seems to be working, but the light is not activating. My oil light also stopped coming on recently. Not sure what’s going on there, but the PTO and brake lights come on when they are supposed to.
The oil and fuel and amp light have the same power feed, black wire to switched power from ignition switch. Either you lost that main feed, or you bonked the lights around while you were in there and they lost connection. They are really bad about intermittently not working because the contact between the bulb and socket is poor. I'd check for your 12v+ feed on the black wire if jostling the lights around in their sockets doesn't help.