OK, I loaded Johnny into garageband and this is what I found
there are 4 separate drum tracks (you know, bass, snare, cymbal, ...)
instruments were all different according to the GM table, so I set
track7 electric guitar
track6 is the lead vocal
track 4 and 5 upright piano
track3 another guitar
track2 fingered bass
This way it seems to work.
By the way, the notation is quite good.