Hmm, so I was intending to replace GM1 SysEx resets with GM2 SysEx resets in my editor (changing 01 to 03 in the reset, meaning GM1 Level 2, and not the new GM2.0).
The first file I tested, the percussion on channel 9 (10) was no longer percussion. I used Winamp with CoolSoft VirtualMIDISynth. I was able to use bank select MSB 120 to set it back to percussion again, butttt, does this mean that for ANY GM2 file percussion needs to be explicitly assigned using MSB 120?
In MIDI Player, any instrument channel with actual instruments showed MSB 121, and the percussion channel (without percussion) showed 0 (and switched to drums when I changed it to 120)
Here are the original file and the modified file (which also adds bank selects if they do not exist).