I have a dual channel agtron blockage and rate monitor for the wired sensors. Channel one keeps giving errors and the problem is in the monitor itself, if I switch cables right outside of the monitor, the problem stays with channel 1. Shut off and cool down seems to be the only solution, then it works for a few seconds or minute at a time. Do I understand that these are becoming obsolete and replaced by wireless mostly now? If so, are there any monitors sitting around unused for the right price? Single or double channel would work, I could always use two monitors, one for each channel, and put up with twice as much beeping...