This gallery shows some photos of my conversion to use a new controller and timing belt e pulleys I made using standard stock items.
I used 2x12 (2 flanges) and 2x60 (no flanges) timing pulleys.

I use a Boxdoerfer MTS3-SDI to control my mount. It is fully customizable, permitting it to be used with any mount witch uses bipolar stepper motors.
The original gears make a 5.22... reduction and the new pulleys make a 5.0 reduction. Because this the original hand controller can't be used

Pulleys needed re-machining to reach the dimensions of the Sirius EQ-G components. All modifications I made all mods. with a mini-lathe and a column drill.
Pinions needed only the bore re-machined to 5 mm (made on mini lathe after careful centering).
The large pulleys needed extensive work to reach the same width of original gear and same diameter & width of the hub. The bore was drilled in the mini lathe to 8 mm.