I agree with the 'tighten the screws' folks, and THEN I'd just shoot about 500 rounds through the gun.
What ordinary 'wear' doesn't smooth-out, you can later slick up with some careful stoning and filing, if you want.
The 'Marlin Jam' seems to be a catch-phrase that describes a generally rare non-issue. ANY gun can jam, but my bolt-actions and revolvers do it more often than any of my 35-years of shooting Marlins. One EXCEPTION is that, like bolt-actions, lever-actions don't generally seem to like you working the action with the gun upside-down or pointing straight up, etc. Few guns do. I learned that the hard way in a deer stand; hard to pry around with a Leatherman 'quietly' to resolve that...
If it is a .44 Mag, and you're emptying the magazine (not shooting the rounds, just removing them) by 'cycling' the gun, it does require paying attention until you get the 'rhythm' of it; once you do, you can empty the magazine with the gun canted to the right 90 degrees, and catch them in one hand as you work the lever. The .357's seem easier to do that way.
Before you try any optical or other sight, borrow or buy a Williams FP and shoot the gun with the rear aperture out of the hole; you'll be surprised how accurate you can shoot it that way, most likely. I can do it better than with any other metallic sight, and as good as with any scope, except if it is near dusk...
