Hi, although it is very easy to put in and remove the spacer ring from the holes at the back of the dynamixel, those spacer rings at the front are difficult to take out. How come? Aren't those holes at the front and at the back supposed to be the same? What is the best way to take out the spacer ring?
Although they are designed with identical size, there are some margin of error due to the discrepancy of material.
In order to pull out the plastic spacer ring in the front face, use a metal stick or a screw(red bar in the image) to leverage the spacer ring while pulling it out from the hole.