Model 57 Discontinued in 1965
It may be hard to find a intact owners manual, they may be floating round on e-bay, for dissassembly the Gun Digest book of firearms assembly and disassembly part III: Rimfire Rifles Revised edition features the Marlin 57
From what i remember of my Dads marlin 56 box mag version of the lever guns was straight forward, the manual would be sweet! maybe a copy from the Marlin Company? in PDF form?