I am having the same problem but mine goes to a minimum of 37 at the heel position. Has anyone found a solution? I don't see any obvious mechanical issues.
UPDATE...ok this was my issue...
In the POD HD500X Pilot's Guide - Revision C : Under Pedal Calibration : Step 5 states "If you get values other than 0 and 255, power off and repeat these steps, starting at step 1."
When I powered off without going to step 6, I would continually get a minimum reading of 37 at the heel position.
I eventually tried going to step 6, saved the setting, and then repeated the calibration process. The values were then correct (0 - 255).
Hope this helps.
~D
