Apparently, the supposed "Morse Code" heard on SFF is that of a Mellotron MKII Guitar, not an actual performance. According to the Recording The Beatles Book, it mentions the semi morse code notes being played upon a Mellotron. Oh and FYI, because I never realized it, that slide guitar on early takes of SFF is also the Mellotron using the pitch bend knob to emulate a slide sound, quite ingenious if I do say so myself.