David's dashboard

My sustain pedal stopped working a few months ago. I finally bought a replacement, but it appears that the pedal was not the problem. Something on the keyboard seems to be wrong. I have a Keystation Pro 88, and the SP-2 pedal. Changing the polarity (holding the pedal down while plugging in) and alternating the switch on the bottom of the pedal neither eliminate the problem.

When the pedal is up, it sends value 64 to the keyboard. When I press the pedal, it alternates between 00 and 127.

Any help please?!?