M-9 looper issues

[William Walker <billwalker@baymoon.com>]

i wonder if any one has been experiencing what I have been with my  
M-9's looper, I have an expression pedal set to control both the  
volume and the feedback of the looper and I've been leaving the looper  
at the front of the effects chain so I can change the effects post  
loop. What happens is after i create a loop, if i am in overdub mode  
and have the pedal off (heal down) so that the feedback is at minimum  
and volume is also at minimum, when I put my toe down and bring the  
loop back up , it has faded away as i want it too, but it is also full  
of artifacts and is severely degraded, not just faded. It may have to  
do with being if half speed, but it seems like a phenomena when you  
leave the looper in overdub mode with ought adding anything new anyone  
else have this issue?
  Bill