Leslie Speed Change Noise

["Spence, Colin" <cspence@nelson.env.gov.bc.ca>]

My Leslie 145 sometimes produces a "pop" or "snap" in the audio when changed 
to fast speed.  This is not someting that you would ever notice in a live 
mix, but I find it irritating at home.  The problem is variable and does not 
occur in fast --> slow transitions.  I use this speaker with an XB-2 and 
1147 pre-amp, but also noted the problem when I first heard the unit, when 
it was attached to an older Hammond of some kind (one of the T series). 
  The 125 I played as a kid had the same problem.  Does anyone know a fix 
for this?