Xylene substitutes can cause problems for an instrument that's designed to 
remove xylene from paraffin.  The processors which do this (Leica first, then 
RMC/Ventana about a year later) were originally designed to remove xylene 
from paraffin, and they do this quite well.

The problem with xylene substitutes is that each compound has a different 
vapor pressure, and the conditions of temperature and vacuum which work great 
for xylene removal may not necessarily do the same for the substitutes.

I don't know what the answer is, outside of a *lot* of R&D from the 
manufacturers and maybe writing different cleaning programs depending on 
which substitute you are using.

Maybe the simplest thing to do is use xylene in the processor?

Cheers,

Bob Chiovetti