XL10t_pulley-D26

XL10t_pulley increased to 26mm around the screw hole. The original looks OK but they have been spiltting near the screw. Note that this probably won't work for the X pulley because of the "ZEST" screw. A normal pulley with lots of fill may be the best thing here.
I've added a second part here - the "r" version has a 6*3mm recess for the screw head.
There is still a problem if the screw is too long.
Based on http://www.thingiverse.com/thing:6822 but redrawn in sketchup.