See link below-
20-50 usd
You can't it is not designed to come apart. Time for a new Scope.
No
About $30
Send it back.
The typical Marlin 39A does not have a scope. They are drilled and tapped that one can be added.
5-100 usd
The Tactical Scope has a colored lens that you can position in front of the scope itself so it is easier to see in dark-ish areas.
It's worth between $10 to $15 used.
I just paid $10 for a used one. Reg.No.F. 7432C
no