I don't know when exactly they got into the magneto business. They are most famous for their 100 years plus of engine technology that is alive and well today and their broad product offering. Their products ranged from lawnmowers, radios, windmills,washing machines, pumps, engines, electric motors to engine accessories and locomotives. Here is some information on their products of the day to share by kind permission from Fairbanks-Morse to keep yours well.
Fairbanks Morse outsourced magnetos for their early engines initially. Many low tension make and break installations used a Sumter magneto and early high tension systems used an American Bosch AB33 or AB34 oscilating magneto.
One of the earlier magnetos was likely the model R. It used an external horseshoe magnet and a wound armature with the condenser in the base and the points in the end .It had a hardened shaft and roller bearings. These were actually very good in their day that were hot even when not in good repair. They were direct gear driven or gear driven with an impulse mechanism inside the gear. The plug wires had threaded ends and screwed into the leadout tower. A two cylinder version was used by John Deere briefly. The wound armature was a riveted throw away assembly that complicates the rebuild process. They suffered from the usual woes of the wound armature and insulation seepage. Some can become stuck as a result. Pop it in the oven at about 200 degrees for a spell and it should let go and slide out. Remember to remove the sparkplug terminal first. The plug wires did not simply plug in, rather they had an end that screwed into the leadout post. The brass screws holding the leadout may appear to have no slots, they are sometimes filled with solder, get them hot with a soldering gun and push the solder out. Sometimes one will see a small brass tag fastened to the leadout retainer screws, that is the spark plug gage. Always check the condenser in the base, we seldom find a good one and routinely replace them. Check for leakage first, then check capacity. Nearly all found will be leaky. replace with a 0.2MFD 400-600 volt polypropylene (Mylar) film Orange drop capacitor.
The next development was likely the model RV. It used an improved design with a stationary coil and fewer moving parts .The points live under the aluminum cover away from the elements but easily accessible for service.The condensers did not improve with age whether installed in a magneto or new old stock sitting on a shelf .It is a rarity to find a good one. If it is not completely dead it is probably headed that way and not very conveniently located to say the least. Always check for leakage and replace if necessary with a capacitor rated at 0.22MFD or so rated at 400 or more Volts DC. The SBE Vishay "Orange Drop" 400 Volt capacitor works well here. There were also multiple cylinder versions made with the condenser hidden in a pocket under the distributor shaft bearing. Lots of bad condensers out there!!! Don't even think about a used or new old stock component.They were not good in the day and certainly have not improved with age. One must remove the distributor shaft and bearings to get at the bugger, but it is a good time to wash and repack the bearings that are probably full of petrified vintage grease. remove the "C" ring (Snap ring) and the flat washer and the rotor shaft assembly should slide out. The condenser is hiding behind the distributor gear in a skinny pocket. John Deere and Allis Chalmers used these. When they are in repair, they are an excellent hot magneto. The biggest problem was often the condenser.
Enter the FM series FMJ.FMK,FM and FMX.. et al and a modern design that endures to this day. They used a stronger more modern magnet alloy, improved condenser and an overall robust design. These were used as OEM by some manufacturers as case and Allis Chalmers. They also have an extensive line of replacement magnetos. They are a modern serviceable magneto with most parts available. Some even at local auto parts jobbers. Here are some factory sales brochures to share with kind permission from Fairbanks-Morse corporation to keep yours alive and well.
Here is a brochure listing their initial FM.. Series line of the day by kind permission from Fairbanks Morse. Enter the modern age. More to follow.
Somewhere in the late 1940's or early 1950's came the FMX series. Here is a brochure for the 1952 model year. Very similar to the FMJ series.