Bill, Bebop, & Mebop:
I have tried all of these suggestions plus all that have been suggested before to try to solve the problem of volume change.
The expression pedal that I am using is one that has performed flawlessly for over three years on my KN2000. Just to be sure, I again tried it on the KN2000, played for 3 or 4 hours without a glitch. Back on the KN7000 and still a problem.
I checked the pedal potentiometer for noise (I have over 50 years of electronic engineering and design experience) and found no noise or intermittants.
The problem at first seemed to be random, but lately I perhaps see a pattern. I have some additional ideas that I will explore and report on later.
Thanks,
Walt