To get a more precise answer to that question, we need some more info about the tractor.
When you ask a question here, itís always important to tell us:
1. The model of your tractor (2N, 9N, 8N, NAA, etc).
2. If it is 6v or 12v.
3. If itís an N, if the distributor is on the front or side of the engine.
4. If it has any major parts that are not OEM, such as electronic ignition, an in-line fuel filter, a Zenith carb, an 8v battery, a side coil on a front distributor, etc.
Troubleshooting is different depending on the model of the tractor, voltage, ignition system & distributor placement & the absence of OEM parts.
And, ask your uncle when was the last time he changed the points/plugs/condenser/rotor & cap.