After thinking about this yesterday, it seems like it needs some support at the thread end of that pulley bolt to keep the belt from pulling it too much at one end. I came up with this idea to replace the wooden circle retainer & be able to adjust the tension with a slotted end of the idler plate. Here is what my 1st design looks like for this. I used a dovetail joint at the outer connection & chamfered a little to make sure it misses the threaded rod. The red parts in the image are for reference on the printer, 5mm threaded rod, bearings & M5x30mm bolt.X-IdlerPulley_rev2.jpgX-IdlerPulley_bottom_rev2.jpg