One problem with the version of the uArm I got through its kickstarter was that it really likes to break servo horns. I probably put it together incorrectly somehow, but the screws that attach the fixed platform to the servo horn and platform bearing were interfering with the bottom of the moving part of the arm, where the base servo mounts. My solution? I bought a stronger metal servo horn and 3d printed an attachment for it.
Once I got that done and working, I ran the arduino servo sweep code to confirm I had good motion.