Problem removing old cogwheel

The other year I installed a Rowan conversion kit on an Orion Sirius mount (different conversion kit to yours). The only problem I had was removing one of the cogwheels that is replaced by the kit. The slot on the grub screw holding it in place was broken and I ended up using a drill and a hacksaw to remove the old wheel. But apart from that everything went fine, and wished I’d carried out the conversion earlier.