I don't see any one else needing to make this but in the spirit of open source hardware I'm documenting the replacement part.
A friend of mine is building a lasersaur (http://labs.nortd.com/lasersaur/ ). The original design for this bracket calls for 2 sheets of 6mm plastic to be laser cut. Being in the US we used what was readily available and approximated the thickness with 5 sheets of 1/8 in. Everywhere else in the design the approximated thickness plates worked out fine. At this location there was enough inaccuracy in the thickness that the sleeve for the pulleys bearings torqued out a bit under the belt tension. With the pulley sitting at an angle to the belts path the teeth were catching causing uneven feeding and the wobbly path pictured.
This pieces is a replacement for the original bracket. It fits very tight and well need to be press fit while using a heatgun to get the bearing sleeve in.