I ended up with two 6 db attenuators in the leads to my two Channel Master 8 port distribution amps. Pixilation on problem channel was not 100% eliminated but greatly reduced.
Putting in two attenuators also helped to decouple the inputs to the two distribution amplifiers as opposed to one attenuator in the main antenna feed.
Note you can do a channel scan with the Tablo and record results but you do not have to change the scan. So if you lose a channel while experimenting you do not have to save the testing results which could affect Guide data.