If you can take your rifle apart to clean it, you are more than capable of installing the replacement trigger from WWG.I hear they are relatively easy to install, personally I take mine to a local gun smith that charges me $20 to install it for me.
Yup, super easy to install and will definitely improve your groups...........if trigger pull is causing them to be too large. Can't recommend them enough. I used to do trigger jobs for $$ and can slick a trigger that's almost as good, and most couldn't tell the difference, so unless I just want a project for a cold winter night, I wouldn't waste my time. In my opinion, the WWG replacement trigger is the way to go.The WWG trugger (Happy Trigger) has a spring between the two trigger parts to take up the slack, and a bushing to hold them together. It is also much more finely crafted, via EDM, for a lighter, creep-free pull. The stock Marlin trigger breaks between 6 and 6-1/2 pounds, not always smoothly. The WWG trigger breaks cleanly at 3 to 3-1/4 pounds, without lightening the main spring. I've installed three so far, and not looking back.