B-Struder - Bowden extruder with MK7 gear + 623ZZ bearing for 1.75mm filament

This Remix is to use a MK7 gear + 623zz bearing.

Beware that the motor spindle needs to be long enough if you want it to support the MR105ZZ bearing, I estimate that it needs to be at least some 20mm long, or more.
By 3D calculations and measuring, I estimate that on my motor (Wantai 42BYGHW811L20P1-X3 2.5A 1.8ºstep) this version would not fit as nice as the 40T design, because of the taller gear that puts the MR105ZZ bearing almost popping out off the motor axle. The bearing holder now has