Printrbot idler pulley with 18 teeth Free 3D print model

My printrbot idler sits too low. The belt does not run paralell to the rods so the tension changes as the carriage travels. I did print a modified idler bracket but I've never fitted it. I don't really like the belt teeth riding on the skate bearing and it turns out adding an 18T adaptor improved the belt angle. Maybe it was planned that way?
I have a feeling this has been done before. Anyway here is a sketchup version. Credit to droftarts who did the hard part.
My X - carriage seems to be running smoother than before.

If your belt is already running true then adding this may be a bad idea.