I found the product page here:
https://scorchedparts.co.uk/products/motor-mount-spares
Are you making use of the slot to slide the wrench to tighten the pinion? This is very common among many brands of motor mounts, I placed a yellow arrow where you would normally tighten the set screw:
can you post a pic of the current situation?
I find it odd that someone would provide an upgrade that isn't compatible with the most popular brand of motor on the planet, shrug