I converted to 12V and pertronix with the recommendded, on this site, 12 volt napa coil that does not require a resistor. I converted about 2 years ago. Tractor was running amazingly well and then missed 1 or 2 beats and quit. It is getting gas and has current at the coil. not sure what or how to check next??. I am inclined to convert back to points,condenser. did not keep old parts. I also have a 48 8N converted to 12v and pertronix with correct 12v coil. It ran for about a year and quit. I replaced the pertronix and it ran for about another year. Was a good running tractor, now it is just sitting out in the field. Recently bought a 2017 John Deere 3038e with loader. I do not like it as well as the Fords. However it has been reliable. For the Fords, 640 and 8N, I have repeatedly bought parts that did not work or were poorly made,i.e. , A new fuel shutoff that will not stop gas flow, points and condensers, complete distributor 8N. I do need to get these tractors running again. Am I all alone in having this many problems with new parts for these tractors?