First Step attach Vtol engine and base to craft with cockpit and run the simulation with the VTOL engine attached.

Second Step Pull VTOL engine away from the craft and let it place it away from the craft (not touching).

Third step pull the VTOL engine further away in any direction as long as it is not touching the craft.

Fourth step press undo and the VTOL engine should go back to step two and turn regular colors instead of grey, It should now work.