My Marlin was always my slickest shooting iron when I got started. I never seemed to miss with it at all. Now those pistolas was another story.
Even if you aren't too mechanically inclined, I think you need to get the manual out for the Marlin and take it apart and do a real good cleaning job on it. They just should not be that stiff at all.
Later you could do things like change the spring out, get rid of the big trigger creep and maybe a one piece firing pin, but first you need to see if it is defective or just has crud in it. M2ยข