MK678G

I have been looking for a nice Mk ll government. Recently located one online, seller said it was in great shape and came with SN test target and box, so I made the deal. Picked it up from my dealer, took it home and attempted to field stripped it. Difficult to say the least. I have had a KP512 22/45 for several years so I am not intimidated by taking it down (or putting them back together). The MS lever was difficult to open, I am aware that is not unusual. The most difficult thing was removing the main spring housing. I watched the YT video and tried the rubber mallet to the bolt with the safety off and trigger pulled. Didn't help. I have never heard of this problem, but since there is a YT video, some of you possibly have had the same issue. Who has a solution?
Another question. The bolt is a one-piece, so I don't have to worry about bolt separation. However, it has a plum tinge. Do some of these bolts go plum after a time?
Last one, serial number is 210-36xxx, how do you I date this gun? The online Ruger chart does not show anything starting with 210.

Try "You Tube" for dis-assembly/assembly. or "AGI" video...

I believe all "Government " models were Mark II pistols,
determine model (Mark II or III).

Yes these semi-auto's are a pain to re-assemble.
The hammer strut has to go into the the notch to properly assemble.