ntchris
commented
2 months ago that hole is for the M3X20mm long screw which goes through the side latch, right? If you could take a look at the part "gear box back", you can see there is a M3 heat insert to hold that M3 screw. so the 3.1mm diameter hole doesn't tap/tight hold the screw, it's not a tap in hole, it just to let the screw go in 4mm deep to better hold it.
The holes showen in Picture are to big. the screw M3x20 should go in the plastic, but the hole is 3,1mm. this doesn´t make sense.