Trap Door rifle question

I have a 45/70 rifle that I'm looking at. When I open the breech and its in the vertical position, I can feel the firing pin protrusion at the face of the breech block. When I push up on it, the pin is easily moved flush but falls right down due to gravity.
My question is, does the pin return to flush as the door is closed on the head of a cartridge or is there a broken spring in there that keeps the pin in the clear until the rifle is fired?
Right now its floating and makes me think something stupid could happen due to the weight of the door.

All of the .58 and .50 versions, as well as the early Model 1873s had a firing pin spring to keep the pin withdrawn until struck by the hammer, fearing that accidental discharge might occur with a spirited closure of the breech. However, the springs were prone to rusting and breakage, occasionally jamming the pin in a protruding position. The springs were abandoned circa 1876 and the form of the pin changed to eliminate the sharp corner (required for the spring but also an obvious point of stress cracking). The combination of rust and broken parts had doomed what SEEMED like a good idea. Those first changes did not completely solve the rust issue, however - which was finally addressed by making the firing pin from "aluminum bronze" (which could not rust to the block) in 1888. For today's shooters, as long as the pin moves freely, there should be no problem. The aluminum bronze pin first appeared as a component of the abortive "Positive Cam" experiment. The latch modification was not adopted, but the new pin was. The PC rifles, just 100 made in the 415000 range, and actually marked "US/Model/1888" on the block, are covered in my new book.

Thank you for the information, I picked up the rifle recently at an auction for the starting bid and have just begun to familiarize myself with the type.
Has your book made its way to the publisher yet? I'm sure it's filled with a substantial amount of authoritive information that I can use.
Thanks again, Brian