Hi Folks, An Optimus 550 - 500cp, I couldn't find anything to date it, I don't suppose they are marked on these lamps? It arrived rather dirty but was advertised as a runner so it was a good starting point. It was stripped and thoroughly cleaned with hot soapy water. Straightened the pricker rod and adjusted the length. The pump leather came good after an overnight dunk in 3-in-1 oil but unfortunately it separated after a few pumps. New one fitted. The surface was speckled with verdigris and the bail was quite rusty. Nothing to lose so I tried a polish to see if it would brighten up - very pleasantly surprised! the verdigris came off and the surface of the fount and the hood came up very well! The bail I got the worst of the corrosion off and gave it a wax to try and keep the rust at bay. Mantle burning-in/shaping. I used a Peerless 24A Mantle which seemed huge and baggy on fitting but it shrunk and shaped very well, with a stunning white light! Mantle has retained a nice shape and burned in perfectly. Very happy. Alec.