If I had a P35 or Hi Power with magazine issues, I'd contact www.chestnutmountainsports.com
or the Hi Power wizards at www.cylinder-slide.com
Karl Sokol is a top rated pistolsmith & did custom work for the FBI's elite Hostage Rescue Team(HRT). Each Special Agent on HRT had 2 Hi-Power 9x19mm pistols in the 1980s/1990s.
I'd buy a few tuned Hi-Power magazines.