Having let some SAE30 soak onto the piston ring overnight, it still feels very stiff to cock compared to my Tempest, but not had chance to fire it yet.
I think the spring guide must be very dry, making the spring graunchy when it is being compressed.
When I strip it down, I am going to polish the spring guide and as much of the inside of the spring as possible. I am quite looking forward to seeing what it is like inside after 70 years, presuming no one else has had it apart!