I don't know if this will help, but if anyone is interested in trying their hand at testing their REO for electrical problems, this is my understanding of how a REO works.
Note: remove the battery before you try any of this and leave it out.
Center pin of the 510 connection ---> firing pin
Firing pin ---> nipple end of the battery, when you press the firing button
(The battery makes the connection from the firing pin to the spring (when you press the firing button). You can use a piece of wire in place of the battery to test that, just make sure the wire is connected so you get a constant, steady reading. A short piece of wire with alligator clips on the 2 ends works well, although in all honesty, it's unlikely you have an intermittent connection in the battery itself.)
Spring ---> body of the mod. Depending on your finish/paint, you may have to hunt for a bare metal spot to stick your probe that isn't touching the spring.
Body of the mod ---> negative connection of the 510 (the outside ring, separated electrically by a small "ring" of silicone (or some such thing)
If all those readings are good and also steady, the problem is not in the mod, and the only things left are the atty to 510 connection, and the atty itself. The atty connects to the negative through it's threads on the outside of the base, and then to the positive through it's center "post".
Note that when you test resistance (or electrical connection), you're looking for a reading of 0 ohms. The reading should stay at 0 and not move around, although if you move the probes, that can make it appear as if you don't have a good connection. Keep a steady contact with the probes and the reading should be steady. If, when holding the probes steady, you occasionally see the reading jump off of the 0 ohms, that connection is where you're getting the intermittent misfires. Also note that when I say 0 ohms, I mean you should get the same reading as when you touch the 2 probes together. If, on your meter, that reads .5, then .5 is what you're looking for.
