I recently purchased a PCR, and as I do with most of my pistols, I read and watched several resources on disassembly so I could polish the trigger parts. But after I removed the decocker, the end of the pin that must be tapped out to remove the sear cage is blocked by a small disc, something I have not seen in any of the pictures or videos. Is this a new meds change, or did I miss something? How do I remove the sear cage on my new '20 model PCR? Thanks.