Does anyone know how to store song data from the Dr 550 to another source? I keep running out of presets to use.

I used to have a DR-550.
It only has MIDI in, so using MIDI is out of the question.
I'm petty sure it didn't have a tape interface for backup.

Sadly I think your stuffed!
I used my unit as a drum module more often than not, triggering it via MIDI.