Tractor keeps blowing 20 amp fuses that control spark from ignition system all the way to the distributor cap. Have 12V at the ignition, fuse box, resistor, starter solenoid, alternator, coil input and output. When I disconnect the wire that goes from the coil to the Distributor cap the voltage is at each of the previous locations. When I reconnect the wire form the coil to the distributor cap the 20 amp fuse blows. In other words when all wires are connected in the start/run sequence the fuse blows when the ignition is placed in start. When the wire from the coil out to the distributor cap stud is disconnected, the fuse does not blow but there is also no spark to the distributor. Any ideas? Thanks