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AP Magneto RX

The AP appeared briefly during the mid to late 1930's and is probably most often seen as OEM on some early letter series John Deere tractors. They were not a compliment to say the least. Mother Deere took  many back on warranty that failed prematurely and replaced them with the Model C and X.  Mechanically, they were robust using needle bearings and a substantial housing. Breaker points were fairly easy to service and the coil was protected under a separate cover.  The rotor was gear driven so there was not a redundant spark during the exhaust stroke to blow the exhaust raincap off in case the charge had not fired on the compression stroke. They used a strong rotating magnet and were quite hot when (and if) in repair. Condensers did not fare well in these devices and should always be suspect when servicing. Always check these for electrical leakage with an automotive condenser tester. If all is well and no leakage, the capacitance should come in around 0.2MFD. Usually when there is no leakage, the device is open and has no capacitance either. Seldom do we find a good one. Retrofitting is a challenge as there is not much real estate under the cover next to the coil, which also gave a bit of trouble back in the day. More on retrofitting this one to follow. With a modern condenser and coil, these are excellent hot magnetos in our experience.  Here is some factory service and parts info to keep yours alive and well.