New Sp1 owner here, the only issue with it and i was aware when i bought it is the ejection port wont stay closed. Once i had the rifle in my possession i inspected and noticed the detent and spring are missing. Numrich sells them but my question is how id this replaced? Cant see a pin or retainer. I dont really want to replace the whole door as the rifle is all original.

thanks in advance

the plunger goes in the top with the spring under it.  then it extends out the housing with a tiny c-clip will keep it from extending past the housing under spring pressure.

Thanks again, i spent all day looking for the answer, i knew the experts here would know.

this ascii drawing below may give you a visual if you need it.

_ [........] - detent housing
=|=SSS=D

c-clip - spring - plunger