LNB voltage is never (OK, never say never!) the LNB. Could you provide a bit of clarity on the time frame? The SK-SWM came out in 2013-14 time frame. Did you get the new antenna in June of this year or a few years back? Something happened in June (this year?) and now it's August.
Have you done the "Calibrate EL" routine and if so, what was the result? Your $400 water heater has NO moving parts so this is not a reasonable comparison.
I agree that you should not be having this many problems. I have an SK-SWM3 that was installed when the unit first came out 3-4 years ago and have not had any issues that were not easily resolved with the software.