Hi Larry,
Welcome to the group!
I had the same issue with my knobs and found a note about what to change to fix it:
In the file: /opt/pidp11/src/11_pidp_server/pidp11/gpio.c
Line 417 in my file:
//knobValue[i]++; //bugfix 20181225
knobValue[i]--; //reverse direction
Line 426 in my file after the above change:
//knobValue[i]--; // bugfix 20181225
knobValue[i]++; //reverse direction
Then from the /opt/pidp11/src directory, run makeserver.sh to compile a new binary.
Note that you may have to install some packages to be able to build on your Pi, if you haven't already.
You will need build-essential at least.