I believe your Marlin lever action rifle to be the model 1893 or the "old" model 1895. It can't be the model 1894 because that is a short action receiver for pistol cartridges only, not the .38-55.
All of the Marlin lever actions are easily disassembled and repaired. Any competent gunsmith familiar with the series (they are all very similar) can do repairs.
From your description, yes, it's likely that the sear/trigger interface needs attention. It's also possible that dried grease and dirt is preventing the sear from engaging. I would suggest a disassembly and thorough cleaning before taking it to a gunsmith. If you are hesitant to disassemble, try removing only the buttstock and spraying solvent or gun cleaner into the mechanism, let it soak overnight to dissolve the old lubricant, and clean again the next day. You can also lean the rifle in a corner and let the action soak in a coffee can of solvent. Kerosene, mineral spirits, etc are good. Avoid fire and spillage, and use proper ventilation, of course.
HTH
John