I seem to have solved my problem, although there is still some mystery as to exactly how. The factory preset that I used to create my patch that I saved to bank 1:1 was one that had the expression pedal assigned to add modulation depth. I assigned the ex pedal to contol the wet dry mix, but did not realise that it was still controlling the depth knob. As far as I can tell, the fix was to double check that the ex pedal was de-assigned for all knobs except the wet/dry mix and I am now no longer having the problems. Used it for a gig last weekend and all was good. You may need to check that the delay time and feedback controls are de-assigned by setting them to thae same value for both the heel & toe positions of the ex-pedal (as per page 21 of the manual.) I would have thought that the problem would not be the ex-pedal itself. I hope this is of some help.