Then some reinforcement from Peter Davison and Resurrection of the Daleks, which might be the only time I ever saw the Doctor with a gun. Not sure he actually fired it.

Oh then if you can find it, The Space Museum where William Hartnell gets all up in one, cackling madly.

the very first Dalek episode (called, oddly enough, The Daleks) has a whole set of scenes dedicated to ripping the alien out of the inside. So it was pretty well established since the beginning.