Looks like a 940. There is a small screw inside the receiver that holds the front if the trigger guard in place. Its a bear to replace. Numerich and feebay both have replacements, about $10 i think. Its not exactly model specific, several models used the same guard.
Stevens (and Savage) are kinda difficult to date at times, but you can get close. Its a Stevens, from Chicopee Falls so that puts it between '42 or '48 up to '60, respectively. Leftover stamped receivers couldve been used for a couple years after that.
There may be a stamp on the underside of the receiver, near the hinge. I think they started that in '48 or '49. There'll be a number and a letter inside an oval. The letter represents a year. A quick google search will find the table, I cant recall exactly whats what. A few letters were skipped also. Serial numbers didnt show up on them until the GCA of '68.
Its current condition would most likely bring around $50-75. Fixing the guard should up that another $10-20. They werent made for collector value, just to use. Theres LOTS of them (and similar) out there.
Do not try to bend the trigger guard. It is cast alloy. You will only break it in pieces.