I was tracing wires from the CC relay on one my E-20 tractors (EC) I unexpectedly discovered the VDR-1 is gone. One end of each soldered lead is still soldered but the other end of each is "dangling" in mid-air with the "body" of the varistor missing. 

1. I found it on the Schematic and Connection Diagram page 7-16 but have no clue what it is doing! What might I expect to be a symptom of its absence?

2. Where/how do I find a replacement?  I would leave what is existing and solder the new leads to the old existing ones. Is it directional? Jim shows a varistor in his catalogue, haven't heard back from him.

 

One other unrelated item. On the same Schematic there is a drawing inset describing a modification issued via letter on June 18, 1973 regarding adding a wire splice and a diode. I am not savvy enough to be able to look at the tractor's wiring and determine if the modification has been done. It appears to involve a relocation of wire 41-01 but I can't figure out where to exactly. (Not something easily described via email w/o drawings and/or photos.)

MIke