Help with engine disassembly

I am currently restoring my first Norton and have an issue in removing the primary. I need to pull the engine sproket to remove the chaincase, and there is a spacer behind the protruding key on the shaft on which it is mounted. With this spacer in place, it is impossible to thread a sprocket puller to remove it. Any advice on how to remove the spacer, or how to pull the sprocket, leaving the spacer in place? Neither shop manual I have shows this piece either in the engine parts list or in any dissabley instructions or pictures.

Pictures are below, assuming I managed to insert them correctly.

In order to remove the washer (packing collar) and any shims that may be behind it, the rotor woodruff key (that's the thin rectangular piece of metal sticking out from the shaft) needs to be carefully tapped/levered out of position first.

Quote from the factory manual: "...Remove rotor key, packing collar and shims from the engine shaft..."

Thanks for the help!