Working on a Stevens Marksman .22 Single shot. Similar to but one step down from a Stevens Favourite . Has any one come across this problem or familiar with how to eliminate lever droop on this one?

In falling block Stevens single shots, lever droop can always be traced back to worn pins and attendant loss of headspace. When closed, the breech block slides up and in to impinge on the case head and/or rear of barrel, if the pins are worn there's too much play to allow that, and the lever won't snap tightly over center and will droop. (Think of a pair of Vise Grips - as you close them there's no resistance until the handle starts to get tight but if you let go it drops open again. By continuing to push them closed "over center" they close up tightly and stay closed.)

That said, on a break-open design like the Marksman if the hinge pin is worn causing the gun to be "off face"*, again the lever won't snap over center and will droop. Ditto if the lever hinge pin is worn. The fix is simple, but requires some tools and skill. The pins can be replaced with slightly larger hardened pins to bring everything back into spec.

Off face: when the breech end of the barrel doesn't meet up tightly to the standing breech, the face of the action. A term used in the world of double guns and break-open single shots.