Consider whether this is worth doing at all, well, apart from re-lubing the internals. These guns except for the very latest (and ugliest) were never powerhouses, 8-9ft/lbs normal, 10 for a very good gun on a very good day. If you were to fit a tighter spring guide - the only reliable way of de-twanging - power inevitably goes down a tad further, too. Having said that if you accept that these are not powerhouses nor particularly accurate guns and instead prefer the experience of shooting a very elegant and vintage feeling gun instead, using the decent open sights taking out tin cans at back garden ranges, making yours shoot smoother may be a worthwhile goal.
**WANTED**: WEBLEY PATRIOT MUZZLE END; Any Diana/Original mod.50 parts, especially OPEN SIGHTS