Tony Duell wrote:
  I don't know the Alto at all, but this sounds a
bit like a Diablo model
 30 drive. In it? 
Most Altos have the Diablo 31 (a variant of the 30 family).  Some have
the Diablo 44.
  FWIW, I have the DIablo Model 30 service mnaual, but
it woudl take a
 little time to find it. 
Bitsavers has some 30-series and 40-series maintenance documentation online:
http://bitsavers.org/pdf/diablo/