OK finally got some work done on the piston on the leg - its blowing my mind.

See video to see my problem.

Piston Test - YouTube

Got the piston working with the spring. Its controlled with 2 locators with aim constants. That's fine.

When I added it to the rig it did not work.

But taking off the aim constants from the locators and placing them on the joints then parenting the locators to them seemed to work. At this point I was happy - until I tried to rotate any joint in the leg in the "Z" direction.

It must have something to do with the aim constants but don't know how to fix this - Plz anyone any ideas ???