Enter the trigger into the housing and line up the holes with a punch and replace the trigger pivot pin. Refit the trigger spring onto the pip at the rear of the trigger and the tang on the housing. Replace cylinder end cap. Slide cocking arm through its housing an locate it. I would screw the barel pivot home now to hold everything in place while you refit the pin in the cocking arm housing. Replace the barrel pivot bolt lock nut. Replace action in stock and refit the stock bolts and trigger guard. Replace your rear sight.
I was surprised that this gun is the same size as the Diana/Milbro 22/23/76 and Webley junior/jaguar/ranger. Apart from the sights being better than the other guns mentioned, I did not think it was much better made. The weak point on the other (non tinplate) guns is the piston can wear at the point the cocking arm pushes on. The Hw25 piston did not seem much better made. Obviously the hw has decent scope grooves but unless you are intent on paying £140 + for a new gun, I dont think the hw justifies the extra money as a starter gun over the other guns mentioned. It seems to plink ok but then so do the others. It,s a pity some of our engineers on here have not made up a better piston to fit the Diana/webley range of small rifles.