Experience has shown that like the full sized lubricators, the model should be primed between 50-100 turns before steam up and at shut down to keep the oil line charged with oil instead of water condensation. This simple good looking hand crank will help in this task as well as servicing as a tell tale that the lubricator is rotating.
To install simply remove the outermost 10/32 nut. Thread on the handle using the 10/32 nut until it stops. Then snug up the innermost nut as a jam nut against the handle.