Hawk foresight...
Have you tried the usual suspects re Webley spares? If you are doing it up as a 'keeper', I'd be tempted to fit a 4x32 scope till the right part/gun for spares comes up.
Wish you all the best. I had a Mk 2 Hawk with .22 & .177 barrels nearly new back in the '70's, & it was the worst gun I've ever owned, bar none. Trigger & safety catch issues were the main problem, followed by piston/ring's. Oh, & a broken stock.
Threw it into a skip - half expected the skip to reject it!
Webley Mk3 x2, Falcon & Junior rifles, HW35x2, AirSporter x2, Gold Star, Meteors x2, Diana 25. SMK B19, Webley Senior, Premier, Hurricane x 2, Tempest, Dan Wesson 8", Crosman 3576, Legends PO8.