OK...........
By now you've probably opened the housing latch (thingie that starts it all) and lifted the mainspring housing lever (attached directly to the housing latch) all the way up to clear the backstrap as much as possible.
And.........the bolt stop pin won't move (that's what you said), probably by twisting and pulling down on the mainspring housing assembly.
My bolt stop pin is quite stubborn, too. Just won't come out with a healthy, twisty pull on the mainspring housing assembly. No matter how hard I pull and twist. Stubborn.
So, what I usually do is either:
1) Take my hard inertial-impact green plastic RCBS bullet-puller device and give the bolt stop pin a good, hard whack on top, or
2) Take a short (2ft long) soft pine 2X4 and likewise whack the bolt stop pin.
[Neither the plastic bullet-puller nor the soft pine have ever marred my Ruger in any way, which is why I use them.]
The bolt stop pin always come out with either (1) or (2) procedure.
I have no (3) to offer.
Putting it all back together after cleaning is totally another Chinese puzzle. Best to shoot it a lot so you clean it a lot and remember all the disassembly/re-assembly steps between times.
FWIW,