Marlin sold zillions of those little rifles and they're great shooters. In my experience, they're easily gunsmithed by the home tinkerer, really simple little actions. When I experience feeding problems the first thing I do is give the rifle a good cleaning. The second thing I do is look at problems with the magazine spring. Dirt and crud in the magazine tube will accumulate over time, and springs wear out. If the spring isn't giving good pressure to feed the rounds into the action you'll have trouble.
There is a
good tutorial on breakdown on these little rifles. The home tinkerer should be aware that after making over 11 million of these rifles, there have been design or manufacturing changes over the years, but that tutorial should give you a good start.