Welcome to MO Unit450! Congrats on that SBL, I just bought one a week or so ago myself! Okay, you will need to disassemble the rifle a little at first to see if there are "rub marks" on the lever. Mine had that and I smoothed them down with a fine sanding stone. If it is still rough to cycle, remove the lever again, and this time, remove the bolt assembly, look the bolt over carefully and smooth down any sharp or rough spots. Re-assemble and see how that feels. Check out the "do it yourself gunsmithing" forum for pics on how to take your Marlin apart, you should do that anyway and file down all sharp/rough edges, the Marlin is not difficult to disassemble/reassemble.
Good luck! and again Welcome! Oh..and pics of your Marlins!!!