I have a new video on the RR1 rev. 2 robotic arm. I show in the video how to replace the gearbox on the elbow joint. Since the gearbox is located practically in the middle of the robot, I have to disassemble and reassemble a lot. In addition to replacing the gearbox itself, the video shows a fairly significant part of the overall design of the RR1 robot and its assembly. The gearbox itself confirmed the hypothesis that the gearbox, or rather its main bearing of its own production, where steel balls are inserted between the printed rings with grooves (see one of the previous videos), does not run completely smoothly. The replacement gearbox uses a standard thin-walled bearing (61816 bearing, outer=100mm, inner=80mm, height=11mm) instead of my custom-built bearing. With the new gearbox, the movement of the robot in the elbow joint is much smoother, see for yourself at the end of the video!