Did a bit of removal, soldering and re-installation today. Shown is the added diode on the underside of the RF Unit (Coil Pack Board):

RF-Unit-Diode.jpg

A 1N914, 1N4148 or similar can be used here. It's going to switch DC only so noise factor isn't an issue.

Per my previous post "It may become more involved...": Apparently it has. Did a DC check of the modification and the "+0.5" switch is doing its thing on both the Aux and the original bands on which it was active. Unfortunately, I lost the Aux band. Remember I mentioned D35? It was removed and the setup tested. Still no joy. I happened to look at the schematics again and see that D26 is active on all 10M segments but isn't supposed to be when the Aux band is active. Next bout with the desoldering station will be to pull it and test my theory.