Early Stevens Tip Up 20 gauge shotgun- firing pin retractor spring

[Rain]

I am the proud owner of an early model Stevens tip up in 20 gauge. After over 100 years, the firing pin retractor spring has become inoperable. Does anyone have an idea of where I can purchase one? Also, is there a model number associated with this shotgun? The serial number appears.to be 1990. Any help would be appreciated!

[PhilC]

Numrich or eBay are most likely your best parts options. Have no clue re: model number.