Tensioner Idler (CTC, Geetech, Pro B)

I bought a cheap printer off ebay, CTC clone, Geeetech, 5 mm plywood. The X axis idler/tensioner self destructed - see photos.
The difficulty with this part is inserting the combination of bearings, pulley and shaft into a single piece of plastic without moving the pulley on the shaft. On my example the pulley won't move and I am reluctant to use much force.

Following design [2] I initially split the part horizontally into two pieces. The split line is slightly above the centre of the beari