The 2 inch idler pulley can be replaced quickly with a 1 1/4" SCH 40 plastic pipe coupler. This will be the same diameter as the original.
The bearing on the grinder will easily press fit into the coupler center. I can supply pics and further answer questions if requested.
1 Cut 1/2" on each side of the center of the coupler. This is your pulley.
2 Save the 2 waste pieces for later.
3 Stack washers on workbench approx. 3/8" high and set your pulley over the washers.
4 Carefully press and tap bearing into coupler until setting squarely on the washers.
5 Cut 1 inch out of each scrap piece so that it will fit inside your pulley when squeezed.
6 Clean and glue the scraps on each side of bearing to keep pulley from coming off bearing while running.
7. Make sure your machine is unplugged then install your pulley on the grinder, replace sanding belt and hand turn watching for any signs of wobble. If none reinstall guards and try it out.