I recently acquired an old Angenieux 17-68mm f2.2 c-mount zoom, probably from the 50-60s. Love the look and feel of these old lenses. It's a nice clean copy. Focus and aperture ring work perfectly. But the zoom ring doesn't turn. It's missing the zoom lever that I've seen on other copies. So basically, I have two questions I'm hoping someone could help me with. 1) Is the lever necessary for the operation of the zoom ring and is that why mine is stuck. 2) if not, can anyone recommend a place for repair.