Buying a new scope won't solve the problem if it's a matter of having the eyepiece focus or the parallax adjustment set incorrectly.

If the eyepiece focus is off, you'll have trouble ever getting the reticle to come into focus.

If the parallax setting is incorrect for your range, then you may be able to focus your eyes on the reticle, at which point the FOV, i.e. the target, would be out of focus. When you look through the scope at the target, i.e. the target would be in focus, but the reticle will blur out and can almost disappear.

Is this the Tasco that comes with certain models of Marlin 60, or a different model that you purchased separately?