Digital BW, The Print

This is weird: I am getting roller tracks and what look like 
abrasion (rub) marks when printing with QTR that don't appear with 
the Epson driver. I'm using a 2200 with UC inks, printing on EEM. 
The image I'm working on has a 100% black ground and that's were the 
marks show. My question is: why do I get these marks only with QTR? 
The printing time is dramatically longer with QTR (6 min. vs 3 min. 
for a 5X7 image); perhaps that has something to do with the 
situation. Any help would be much appreciated. I really like the QTR 
ink tone options and would use it even with the long print times, 
but this marred surface problem just won't do....
BJM