Lights Out??

If you have a multimeter, check the voltage at one of the lights. If not voltage, I'd check to see if there might be a fuse some where. (seems like there is one on the switch, not sure if that is original or aftermarket) if you do have power at the light, check for resistance across the bulb, or continuity, which ever you prefer.

Regards;
Bill

My tractor has at least 6 coats of paint, and I found the most sure fired way to get a good circuit was to run 2 wires to the lights. One for the +, and one for the -. Again, it does not matter which side the switch is on.

To test if your bulbs are good. Make up 2 lengths of wire, and connect the bulb to + and - on the battery terminal directly (with the tractor off). This will prove your bulbs are good.

If you want to prove that your body is grounded properly, take a multi-meter and switch it to Ohms. Most have an audible setting so that if you touch the two leads of the meter together you hear a chime. This is called testing for continuity or in GOBT (Good Ole Boy Talk) "ringin it out". Once you have the meter set correctly, touch the 6V+ terminal (you said you have 6V+ ground) to the body of the tractor. If it rings, move to the light terminals. This is testing that the two ends are "electrically connected" and that current will flow.

Also do the same test on your light switch terminals. If you connect the 2 terminals on the switch to the meter, it should chime when the switch is made.

Hope this helps.