Welcome to the forum!
I have one of the Polaris 130 scopes. Unfortunately, I removed that gear while experimenting with other things and I think it ended up in the trash. Secondly, I am in the US.
I can tell you some things related to that part, though. The first being that it does not fit any drive unit that is currently being sold. That mount was apparently developed for something else Sunny was making in the past. It does serve, however, as a control knob on that side of the scope.
I purchased on of the first batch of motor drives for that mount. It has a flexible fitting that attaches to the connection where your manual control knob goes. There is no clutch or way to re-attach the manual control knob with the drive unit on the scope. After a while, I took the drive off and went back to manual. It seemed to me to be the easier way to go. Some of the really old motor drives, for similar mounts years ago, cam with a gear in the box that meshed properly with the gear on the drive. The center hole might need to be drilled out a bit to fit the shaft on this mount, but that might be a solution to get the drive on the correct side of the scope and have a functional clutch.
Something I did to help was to modify the control knob cable length. I cut the cable with a hack saw a little less than an inch from the metal end that attaches to the mount. I then took the plastic knob end, pulled off the plastic sheath from the cable, and unwound the cable, strand by strand, pulled them back until I could reach all the inside strands individually. Using a pair of pliers, I jerked all the strands out, starting with the inside ones, and cleaned out glue residue on the inside hole in the plastic knob. I then had to file the metal ends of the cable left in the metal fitting in order to get it to fit inside the plastic knob (rough saw cuts) then set the knob on a table with the cable hole pointing up. I stuck the cable into the hole, saw how much cable was exposed with it seated in the knob, and cut a small piece of the sheath to fit that exposed cable. I poured some ordinary white glue into the hole in the knob, inserted the cable with the little piece of sheathing in place, and wiped off the extra glue. I let the knob set for a couple of days to dry completely.
With that stubby control knob, I can reach it from either side of the scope. Plus, it does not interfere with tube position the way the longer length did when the optical tube was on that side of the scope. With that done, I have not missed the gear you are asking about, or the motor drive. However, I am not trying to image with the scope.
Hope this helps,