Excellent write up. Easy to follow with the pics. Good on you for giving it a crack, it's certainly not an easy task.

This is what the forum should be about, not whinging and bitching farken!

I'll add one thing on the topic. Be super careful if the motor is plugged in. If you accidentally move the arm it can start a full rotation even if the switch is off. They are reduction geared and can easily do some finger damage/severing. So disconnect the plug at the first opportunity.