Digitech PDS-1002 Issue

[Stratomaster]

Howdy,
     I have a PDS-1002 that has a strange problem.  After some time, the pedal will all of a sudden generate a low end, staticy noise that gets looped through the regeneration path.  This static will continue and get echoed though the circuit.  The only things that stop it are turning off the effect and waiting a couple of seconds or turning down the regeneration knob to '0' and turning it back.  However, the sound will often return within a few minutes.  Also, the infinite repeat switch works fine, but needs to be pumped about 10 times before it works normally.  Any insight would be appreciated.
-OMJ