Sorry, but an SWR (standing wave ratio) meter will not help you here - it reads the transmission line reflections from a radio transmitter which you are transmitting on - has nothing to do with reception.

OTA digital signals are very prone to disturbances that may have only caused a little snow or ghosting on analog signals. A large tree swaying in the wind in a direct path of your antenna and the transmitter could cause a situation like you described.

Get an antenna "pre-amplifier" that mounts at the antenna - often a two piece amplifier and power injector system - not a "distribution" amplifier that is meant for feeding multiple locations. Then use the digital tuner signal strength meter to aim your antenna on the weakest station.

Hi Bill. So the SWR meter isn't helpful and remains on the shelf. I have a SP-813 amplified antenna on the way that should do the job. I found the compass direction for the stations I receive. The one I had the trouble with was about 5ð off so I reoriented it and that helped a little.
Thanks for your advice. I appreciate the help.

Dave - hope the new antenna solves the problem. Please post a follow-up as to how it works for you - it's become a fairly problem common that lots of people have had to deal with.

What's really amazing though, is that the pixelation and breakup always occurs at the best part of the movie or football game!

Or, NASCAR race!

Follow up:

Since OP I bought an amplifier for the square-grid antenna I've had installed in my attic for years. It did help some.
Bought and installed a lava motorized antenna. It does ok, but having a motor on it is pretty-much useless, since the controller does not indicate where it's is pointing or what direction it is rotating. Basically it's a set-it/forget-it type.
I also bought an SP100 omni-directional antenna. It too does ok and found a few more channels. I do not have a signal strength meter but have one on the way. It, hopefully, will help tune the antenna better than me using only a compass.
I will try to mount the omni unit outside and out of sight to the HOA spys. It doesn't look like tv antennas once did. Looks more space-age.....frisbee with a 24" wing on each side 180ð apart.. That installation will be the best I can do given where I live. That will involve a little more work (grounding the mast and grounding the cable-shield). I think my biggest problem with OTA signals has more to do with the 70' Red Oak tree in my front yard tho....