tear it down & clean it up..........got a buffing wheel ?
buff/polish pivot points.......
'72...?...pull mag spring & follower...it'll be grubby........clean inner tube...reassemble...........
do not overtighten gate screw........
http://marauder.homestead.com/files/TUNING_M_1894.htmhttp://www.ktgunsmith.com/marlinjam.htm