Found suitable gears and motor, installed them right away.
Step one: try to find the suitable location for the motor for correct gear meshing, fix it with a tape:
Then, use some instant glue to fix it in place, add hot melt glue to further reinforce the position.
Finally, solder cables and also standard jet for connection to the controller box. Add hot melt glue to insulation the bare end of the cable.
A short clip before the soldering work to show the gear meshing: