Remove the grips , use the pin to capture the mainspring .
Take a magic marker & (dot) the peices to keep em in the correct orientation!
Depress spring ( I use a small vise with a peice of leather to hold the strut) then a small pair of vise grips clamped to the stirrup , carefully remove the pin & stirrup.
This is a stamped part so now is a good time to smooth up the ruff side!! & don`t forget the slot in the stirrup!!
Reassemble in reverse order keepin the marks oriented correctly .
I make a tool for disassembling the ruger GP/SP? SIXes with ,you can see it in reoccuring items section !!!
It`ll make it easier & safer , I promise !!!
GP