B64 Arm Mount Insert #1 Vertical Offset Hole

thingiverse

It slides neatly into place where the standard one fits. There's a bit of wiggle room due to the inherent looseness of 3D printed parts, but so far, none have given out on me. These custom ones cost significantly less than the originals. I had to tweak my printer settings to -0.05mm horizontal scaling during printing, though your machine may handle it differently.