specific instrument is jaring with headphones compared to other SF's

I'm specifically talking about this song: https://github.com/OpenTTD/OpenMSX/blob/master/src/chemistry_lab.mid

I can't quite pinpoint what instrument it is, (and haven't a clue how to solo each), but If I load up OpenTTD with any other SF it goes away.

I quickly fired up polyphone and 00:54 Synth Voice doesn't seem to loop too well, key 56 and below, 57 sounds fine. that could be it.