The TG975 series sight was designed to fit many different Marlin rimfire models. It was designed primarily around the model 60, but again, will fit many other Marlin .22’s. Most Marlins will fit up with no adjustment required to this front sight screw.
One option is to try the original screw that you removed and see if this gives you a secure fitment. Another is to work this supplied screw down just a little bit at a time on a file, or even sandpaper until a good fit is achieved. We only have one length screw available for this part, and sometimes these do require just a little bit of fitting to work best on your specific model Marlin .22 rifle.