I'm currently working on a Rainbow D2, and I'm having trouble removing the aluminum housing for the fans.  There are three of them stacked together for each fan stage and they are a very tight fit.  From the look of the motor, I doubt that it has ever been serviced.  I've thought about WD-40, but they are so tight (meaning air tight) that I don't think that will work.  I've also thought about soaking the fan area in soapy water.  They'll need to be washed anyway.  I can force them off, but that would damage them.  And I really would prefer to keep the motor as original as possible, so I don't want to buy new fan staging.  Any help would be greatly appreciated.  Thanks!