Let me be the 1st one to welcome you to the friendliest forum in the world. I'm not sure why your post is not receiving the love from our usual welcoming party. Perhaps everyone is out partying after being lockdown for so long.
There is no such thing as a dumb question here. We are all here to share and learn. I've asked enough dumb questions in my lifetime to fill a whole room.
May your hobbies fill your life with endless hours of enjoyment.
The 215 is a quite common movement for a Patek Philippe, but as with all expensive watches the replacements are expensive too since they aren't mass produced.
Here you got one at the bay selling the wheel you ask about, the rest of the parts are out there too. https://www.ebay.co.uk/itm/Patek-Philippe-Geneva-Cal-215-part-1x-under-crown-wheel-420-diameter-3-4-mm/133217216347?hash=item1f045d675b:g:ywkAAOSw4bhcJQ0P