Hi Willem,
just forget about apc to smf convert for the melody. If your goal is a lead sheet just with melody and chords, you do not need the auto accompaniment in the midi file so ignore apc to smf convert. Apc to smf is only needed if you want to score the entire arrangement with up to 14 staves for each part; [melody, counter melody,] bass, drums, piano, guitar, strings, etc etc !

Just save your easy record as a gm midi, panel header on, in the normal save to SD or floppy procedure so it will load into your computer sequencer, remembering the advice on controllers and quantise - this will give the cleanest score requiring the minimum editing. You will have no accompaniment playing, but that does not matter to get the melody score on channel 1. Then type in the chords quickly using the trick described if you can't remember them all.
Lead sheet complete