Good advise to leave the spring as is while you work on getting that upper screw un-done.
Once the screw is out, I usually just place a tapered screwdriver blade into that clearance betw the spring arm and the frame that is noticable in the pic.
Tap the blade down in betw the two and it'll push the arm of the spring away (compress it) slightly. That takes the pressure off of the top lever spindle and it's free to exit thru the top of the frame.
Take care tapping on the extreme end of the top lever spindle where the small screw hole is.
The part is case hardened and that end often got near through-hardened because of it's small size.
The result is that the end is brittle and can break easily often with a piece of the internal threaded tip chipping off.
The hole is a standard 4-40 IIRC.
It doesn't take much compression of that spring arm, so it one screwdriver blade doesn't do the job because the taper isn't enough, try a different screwdriver with a little more taper to the blade. All this just to avoid simply twisting the screwdriver to push the spring arm aside,,which you can do of course. But that can leave marks on the spring which don't do it any good for it's service life.
Tap the over hanging arm down gently to kick the back end V up slightly and you can work the spring out of it's cavity in the frame to remove the spring.
Or,,You can also put the frame straight up (tang up) in the vise and a stout bar of brass or steel behind the long arm of the spring. With a hand on both ends of the bar, pull towards you and pull the spring from it's seat in the frame.
I favor the former as it is a bit more controlled!
But I saw both methods used at Marlin in the early 70's in the repair dept when elderly LCS came in for repair.
Only 2 of the 'smiths in the repair dept worked on them.
Shortly after that, Marlin started to decline any work on them (and any older MArlin firearm) with the excuse of 'no parts available anymore' which wasn't true. We had ton's of parts.
