If you’re finding the plastic gear on the blind controller is wearing and the motor spindle slipping as I have (my blinds are over 5kg). I have designed a new gear that uses a metal coupler held in place by a series of short M3 screws. I find the 6mm option works perfect and they are available here: https://www.banggood.com/custlink/KKDGZIzOGb
Note you will also need to print the revised gear surround to accommodate the slightly larger gear. 3D files are available from thingiverse.