Hi there! I'm pretty sure this isn't the best place for this, however, I'm desperate, so I figured I'd try.
I've got a FARO Arm IND-02. It's really quite old at this point, from 1993 or so, I believe. We use it to digitze huge twisted panels of glass, so that we can position them in 3d and then nest them into eachother, for placement on the celing. We purchased it secondhand, and it's been great for about a year and a half. Recently, as in 2 or 3 weeks ago, it's no longer really functioning properly. I can draw a square on a table three times, and get three almost-squares in three completely different places on the computer. Needless to say, digitizing a large twisty glass thing is no longer possible. I'm looking to figure out a way to get it fixed. I brought it by Dimensional Inspection Labs, just to make sure it wasn't simply out of calibration, and they guessed that one of the encoders was probably out, but they weren't really sure, and they certainly had no idea which one it might be. FARO no longer supports it, and doesn't have any idea. (aside from posting on a forum, which is oddly enough, what I'm doing right now!) I figured perhaps since y'all use these things, maybe you'd know of the next step or two for me. I've found where I could buy matching rotary encoders, and the like, but I'm really not sure how I'd test what's broken and what's fine.
Well the way I fix things, is to take it appart and see what's inside. Check what they have it there for encoders, is it glass circle with lines or some soft of a magnetic deal. I don't think they made the encoders so you will see a brand on them, if so then yo can get a wirring diagram if the company is still around. Then you will be able to test each encoder one by one with a o'scope or maybe a regular tester. If the encoders work them move to the interface card. Look over the wires in the joins the connectors any other electrical things that move.
It could be as simple as one of the wires to the encoder being broken or twisted off. The older Faro's have a hard stop that prevent you from rotating the arm more than 360 degrees to prevent you from twisting the wires off.