I have 2 Northern Radio Company type 105 Model 4A F.S. Keyers and need a manual, or at least a schematic. One of them has an additional military tag on it that reads: "1760-213575937 P/N 2C2711-2 JUN 55 USAF". Any info on these would be helpful, and I'll be glad to pay for a manual, or to have yours copied...