Yes, they were changed rather early in the piece, because when I
first rode them, they were very, very quiet. nowadays, when you
ride them, you hear this noise, which sounds like that of a vaccuum
cleaner. This is a fan of somesort, and is typical of all Voith
gearboxes (the TIBS articulated buses with Voiths have this noise,
as well as all the VSO's except 9888Y, which has a ZF
gearbox).
Down with Voiths!