...What seems to help is to unplug the ACC input to the radio from the controller switch, and simply adjust the antenna coil to get the strongest RX signal on a given frequency. The SWR warning goes away...
So the automatic controller can't tune the antenna to resonance, but it can be done manually and
the antenna can give a low SWR? Have you confirmed that by putting an SWR meter in the line and
checking the reading? You should be able to tune it manually for minimum SWR or maximum power
output. If so that would seem to indicate that the problem is in the controller, not the antenna.
You might have blown a diode in the phase detector or some such problem.
My signal is not coming out well...folks on Kauai Island hear me, and on Oahu, but Big Island (which should be a cakewalk for 100 watts on 40 meters...and used to be) is a challenge.
Is this with the antenna tuned manually for good SWR? It might be due to propagation - 40m hasn't
been its normal self for short to medium range coverage for the last few years. You can go here:http://www.ips.gov.au/HF_Systems/7/1
and run a "Local Area Mobile Prediction" (LAMP) chart for the current ionospheric conditions. It will
show you what frequencies are open at what times of the day for distances out to 600 miles.
It looks like 40m should be open for you for perhaps 7 to 8 hours per day, while this far north it
rarely opens for distances less than several hundred miles, and then only at the peak of the day.