Looking at the thumb safety it appears that a simple plunger at the base slips thru a matching hole in the frame to allow depressing to enable the pistol to fire.
The pistol locks and cocks fine, apparently, but the safety is stuck in the “Up/Safe” position preventing the trigger moving rearward.
Has anybody had this issue or seen it before?

Whilst cocking it try holding the safety down before you return the barrel to firing position. You may find the striker doesn't actually cock. You may feel the striker spring tension on the barrel as you return it to firing position. Your safety will be free to move but the striker is not cocked. If that is the case your cocking lug on the barrel is too short to fully cock and jams on the safety.

Rookie mistake… The protruding cocking indicator had me assume that the pistol was cocked… It was not.
Properly cocking the gun proved it totally fine, just my mistake not realizing how far out the indicator would actually protrude when fully cocked.

So I moved to RPM “2”, and found what appears to be a broken firing pin spring… Anybody know where a disassembly procedure/diagram might be found??

With the frame on its side, punch out the two pins that are about 1/16 dia.on the slide that locks the barrel down.
There you will find two springs, probably not broken but relaxed and lost tension. The problem is going to be finding those springs because Jim Rock custom made them, anyone that has extra’s knows that those springs are what keeps the gun from being a paper weight.
I asked Rock for years where he bought them, he never would say. He sanded the outside surface of them to remove some of the tension from new. Good luck with your project

Thanks for a VERY helpful reply.

There seems to be no tension at all, and when the pistol is cocked I can squeeze the trigger then use my thumb to push the firing pin indicator to the fired position.
While pushing the indicator in there is a definite “dragging” type of resistance that leads me to think a spring might be broken and creating friction where there should be none.

I REALLY appreciate the advice.