Where did you get the first replacement firing pin? Was it from Ruger? If so, I'm sure they'll make it right.
If not, you may have gotten a poorly-made part that I've heard about on PerfectUnion.
Apparently someone is making various Ruger parts and selling them to various distributors. Some (or maybe all) of these parts aren't up to snuff.
Now, it's my understanding that Ruger WILL NOT sell firing pins to anyone. Ruger insists that they be fitted to the rifle by a Ruger tech. I assume this is for liability purposes, probably to avoid slam-fires and/or FA bursts.
So, if I understand that you acquired a Mini firing pin, I suspect that it was either not an original Ruger part, and/or not properly fitted.
IIRC, sending a Mini to have TWO spare firing pins fitted, and TWO spare extractors fitted will cost you about $110, parts and labor.
And that's what I would do.