All that heresay, rumour, and guessing in the blog post Manipulator Arm Modifications may have actually been correct, as the redesigned robot arm performs flawlessly.

The original parts on on the left in pink, the redesigned parts are in the middle in orange, and some failed and doubly-redesigned (mistakes were made) parts are on the right.

(Image link: http://imgur.com/E225L7D)

The arm's backlash when swiveling wouldn't be fixed with additional ball bearings -- it needed a better gear.

Gears are complicated, so designing gears with dimensions that both fit the larger swivel gear perfectly and have major diameters in between the two provided by the original model was rewarding. Below are the two new orange gears with 23 and 24 teeth, the 24-tooth version installed, alongside the original pink gears with 22 and 25 teeth.

(Image link: http://imgur.com/3N2iBVF)

The turret's lowermost axel diameter was enlarged to 6mm, thinking of an M6 threaded rod or bolt. I chopped the ends off an M6 bolt with plenty of un-threaded length. It works much better than the threaded rod that was in there before, as the threads tend to move pieces side to side, pressing them together and making the whole thing stick.

(Image link: http://imgur.com/o5tURhD)

Here's the money-shot:

(Image link: http://imgur.com/flkBh5L)

I'll put the actual performance testing results in another post. (This one is just to show off!)