Marlin 890 help

[hawkenhunter87]

This is my first post so I just wanted to start off by saying hi. I was at a gun show and picked up what looks like an old marlin. The only identifying stamp on the barrel says Marlin model 890 .22 long rifle only. Beneath that it says micro groove. There is no serial number. I have been unable to find any information online about it, and have requested a manual from marlin but they sent me one that didn't fit the gun. I was wondering if anybody here knew anything about it, and if they could tell me how to disassemble it for proper oiling and cleaning, as well as why the action doesn't stay open upon firing the last round. I'll upload some photos soon as I figure out how.

[hawkenhunter87]

Sorry guys, figured out my error. It's a marlin model 89c not an 890. No such thing as an 890. Quick question still though, is the action supposed to remain open after the last round is fired or not? It doesn't on mine.