I don't know if anyone else has had this problem, but I built my Wilson 2 with the smaller idler pulleys and they didn't hold up to well. While printing, the x idler pulley started making noise and sounded like a rocking chair going back and forth. What I found was that instead of the pulley riding on the bearing, the whole pulley was spinning on the 3 mm screw and overheated.
This may have been from the tensioner I printed was not quite right. I'm sure the ones that come with the kits are fine. However, I wanted to use a larger 20 tooth pulley that is easily accessible from a place like Amazon, so I modified the tensioners to hold the GT2 20T pulleys like this one.
I started with the larger tensioner for 11 mm pulleys that Marty had on Github because it had more clearance and allowed for a larger 5 X 25 mm screw. I added a 1 mm bearing surface that should hold the inner bearing still and allow clearance for the sides of the pulley. I posted both the sketchup and STL file on github for anyone who may want to also try the upgrade.
Here are some images of the new tensioners and pulleys.
While assembling the pulleys, I used lock nuts and tightened the 5 mm screw to the point it would not spin, but not too tight to add friction to the pulley. So far the printer is working great and the new pulleys are holding up. I will post new updates if any problems come up.