Infernal Robotics, parts locking up

[Da Vinci]

So, here's the situation: I'm running a small Mun base. It has a number of ISRU modules, that produce fuel to refuel my reusable landers. My intended mode of operations is that there is a rover that shuttles the fuel from ISRU module to lander. To implement this, all modules have a Jr docking port, and the rover (essentially fuel tank on wheels) has an Infernal Robotics parts arm, with a Jr docking port at the end, to connect to various modules. Now, the arm has a rotator at the bottom, a powered hinge on that, a hydraulic cylinder and a powered hinge and docking port at the end. I can 'dock' with the ISRU module just fine, transfer fuel between tanks etc. However, when I 'undock' from the ISRU module the 'rotation' on the hinges is reset to 0, whilst the hinges are still rotated. So my arm is still up, and when I attempt to rotate it down again, because it is already at the limit, the entire vehicle rotates, rather than the arm. Am I just trying to do something that won't work, or does anybody know how to prevent the limits from being reset when undocking? Both my basic Kerbal and mods are up to date. Cheers!