Hello Dubmuffin I cannot offer anything useful to solve your problem, but I noticed that you mention your old Oregon Sensors. I am desperately looking for an Oregon barometric sensor(BTHR918N) which goes with the Oregon 928N and wondered whether your kit had such a sensor that you may be prepared to sell.
I hope I am on the correct page for this enquiry. I have had an Oregon WMR928 for about ten years which has worked perfectly. However, the pressure sensor, which displays indoor temperature and humidity as well barometric pressure, has just died on me and now only gives extreme readings(600Mb or 1050Mb). The temperature part still works. I have tried everywhere I can think of to find a new unit without success. I just wonder whether anybody has an old unit that displays the correct pressure which I may buy so that I could use or transfer the pressure sensor within the unit to my U/S one.