Oh, and at the risk of offending anyone any more than already and unintentionally done... the slots in the speed ring (cam assembly) of a Graphex shutter are designed to be greased, as stated in the Graphex repair manual. Friction wear of any magnitude is unlikely if shutter is properly overhauled/maintained. This is not my opinion, it is documented in Fig 14 of the repair manual (and just happens to be consistent with that of German-made Compur shutters).