Wow! I've never visited this forum before, and I'm thrilled to have the help that's coming my way....thank you.
Here more info on the various X10 devices operating around my house:
Active Home Pro is runing on my PC and connected to house power by the plug-in USB module.
There is a plug-in controller in my master bedroom set on the A channel.
There are two wireless-to-X10 receivers plugged into house power, one on the A channel, one on the B. There are three wireless transmitters used to control these two channels.
There are several wall switches, appliance modules, and wall duplex outlets of the X10 variety on either the A or B channels.
The wall switches in the HT that aren't responding are on the C channel, and are not listed in the Active Home program because I don't need to control them from anywhere but the HT itself.
When I check the 'find other computers' in AHP, the C channel shows number 1 as Red (this is the main lighting group), and all other numbers as Yellow...none is Green.
The Pronto has rechargeable batteries and lives on the charger when not in use, and it continues to control everything else. The 6-in-1 flashes its red light when activated, but maybe that's not good enough.
So now I have tested the HT switches using the old 543 and the new 543 and one of the wireless transmitters and the 6-in-1...no joy with any.
I am unacquainted with the idea of a repeater. The bridge connecting phase 1 and 2 of the house power is strictly a passive device so far as I understand it...just a capacitor I think.
The loss of control over the HT switches is not a major problem, just a loss of convenience....plus I like to solve problems if possible.