The model C was an early rotary magnet product that was a big improvement over the previous reciprocating designs. It had fewer moving parts, was totally enclosed and did not require any tempermental trip mechanisms.
Here is an early owner's brochure.
The "Use Light Oil" instruction scrawled on the housing was interpreted by most as to use no oil.
Most model C's never got lubricated. If you don't know when it was oiled last, let 'em have it with some 30 weight till it overflows. None will get near the points and any excess will keep the dust down. For the breaker cam smear a small amoint of a modern molybdenum wheel bearing grease. Molybdenum grease is usedfor high temperature installations like disc brake rotor bearings and also resists flinging and wiping off. Coat the cam with A blob the size of a match head.
The early phenolic condenser shown as part" X1413 was a problem child to say the least. One will rarely find a good one. Always check this one for electrical leakage with an automotive condenser tester. Most will be defective.
Unfortunately, your magneto is probably out of warranty.
Here is a later instruction and parts brochure tp keep yours alive and well.
The model C used two sleeve bearings inside a skinny tube and were oiled by a felt wick with a steel disk and a scraper that slobbered oil onto the shaft.The tag says to use light oil, this is usually interpreted as once every 50 years whether they need it or not. There are two 1/4" slotted pipe plugs, one on each side that let one add oil to the felt wick. Unfortunately, these seldom if ever got oiled. We would remove each plug and when the mag is installed, and let em have it with the pump oiler till they will take no more, or lay the mag on its side. The oil can't get on the points. Worst case if you get too much is that the excess oil slobbers out a weep hole in the bottom of the casting and keeps the dust down. Those of us that have a funny sounding green tractor that only hits on two cylinders are all too familiar with these. Here is some information to share to keep yours alive and well with kind permission from Standard Magneto of Chicago who still has many new parts for these. Always keep the mounting bolts snug, as with some a loose or missing upper bolt can cause the magneto flange to break off. Also be mindfull of excessive endplay in the governor shaft of the green two bangers, that will beat the coupler of the mag and can cause the governor shaft to fall into the engine. When they are in good repair, they work well.
The points are set at .015". Sometimes with new gaskets or changes in weather the cap will settle or move slightly and may need the points reset. If there is still meat left on the points, by all means reuse them. I have had the best luck with genuine Wico points. Some aftermarket knockoffs have a sloppy fit between the rocker and the steel bushing causing the points to slide before opening. Some attempts use a plastic rocker that is tight on the steel bushing and causes the points to hang up and float. This is very annoying. The Wico points and possibly others used a bronze bushing in the rocker that fits well and moves freely. Many times one will replace the points and wind up in worse shape than with the old points . As always, make sure that the contact surfaces old or new are lined up for best results. The usual woes with old condensers appear, too much Oregon Rain in the wrong places. Sometimes you will see a plastic encased condenser like in the picture. This was an early attempt and they are seldom good. As always, check for leakage first, then capacity. If they are leaky, replace them.
Here are some of the common parts to be encountered. Many of the impulse parts are shared with the Model XH series with exception of the catch plate and impulse nut. The model C used a 3/8-16 thread and the later model XH used a 3/8-24 fine thread probably for less chance of coming loose.
As with any early magneto ignition system, alsways use solid metallic non resistor wires and plugs.
Sorry to say, your mag is probably out of warranty.