Help with calibrating a robot arm

Hello,

First, I just wanted to say thank you for the .urdf importer. Its making a huge difference in what we are currently developing!!

Im a little stuck in calibrating the imported robot to behave like its real-life twin, and Im hoping it will seem trivial to someone here. The arm seems to be straining a lot during operation and stationary joints are slipping.

here is the non-embedded gif: gfycat.com/impishgrimafricanwildcat

You can see that when changing the target value, the higher hierarchy joints are not stiff enough to prevent the operated joint fom translating. The lower arm joints should be a lot stiffer. Is there any way to remedy it? I have currently set up the stiffness, damping and force limit to achieve realistic degrees/second joint velocity. I cant seem to get the remaining joints to be stiffer no matter how I adjust the global controller variables.