The annoying drone in the MIDI of the Hutton tune is a result of the variant measure markers "a" and "b" being interpreted as chord symbols (lowercase indicates an alternate bass note rather than a chord). You can rectify it by prepending a circumflex in each instance; this indicates that it is simple text to be placed above the staff: "^a", etc. Similarly, the transcriber used S to indicate short breath marks (as described in the note in the header), though in standard usage S is rendered as a "segno" mark. You may be able to fix this by redefining the S macro:
     U: S = +shortphrase+
or, if you prefer,
     U: S = +breath+