I have a pneumatic cylinder that mounts to a fixed base and an arm.  The arm is pinned to the base on one end and the cylinder mounts to the arm about halfway down its length.  I can use a hinge mate to secure the body end of the cylinder to the fixed base, but once I mate the cylinder to the fixed base I can not mate the cylinder to the arm, as it over defines the assembly.

Any help would be greatly appreciated.