Magnetos

you might try giving the coils a couple of coats of clear poly urethane. Restored 11 older motorcycles and the coatings on the coils looked good but had micro cracks in the bakelite, Moisture would wick in on humid days or rainy days and they would sputter and arc out causing rough running., same with old plug wires, and plug insulator caps, swap out with some good ones and see what happens. Just a thought

thanks for the advice. I had mine cleaned-up and rebuilt (with new parts from Fresno) and there is still an intermittent issue going on. I will try again to have the coils replaced to see if that works... but solutions seem to be running out

Stick with the Eisemann mags, old time bullet proof with no 500 hour inspections required. Get them cleaned and adjusted and keep on flying.
Eisemanns were used in everything from 1930's farm equipment, snowplows, combines, tractors. Parts are easy to find in the midwest and northern Maine old time shops. Just MHO Still usiing mine from 1946

Looking to upgrade my Eisemann mags to Slick (4301).  I can find some package deals at Wag-Aero, Spruce, and Chief ...however I am having difficulty in locating the mag drive gears (which are different between Slick and Eisemann).  Any tips on where to find a couple new drive gears which are Slick & C-85 compatible?