Good luck with the trigger mech, I bought a 75 four months or so ago (fortunately cheap) & it turned out to have been resealed, unfortunately some had managed to jam it cocked (bear trap mech) & trigger parts were damaged. Got it apart ok but new mainspring set required, neither Chambers or John Knibbs has springs & unknown when they will get them in. Trigger parts are now listed as obsolete & unobtainable.
So it looks like i have no option but to break it.