We had the "bubble" problem when we first started using our Cadenza and
Sequenza. (our problem was not the machine since one of ours is manual the
other automatic)We do not use any detergent in our solutions so we ruled
that problem out.  That left us with the slide/coverplate connection between
the two machines. What we figured out with our system (may or may not be
your problem) is that we needed all of our solutions to be at the same temp
(room temp).  We also use aqueous peroxidase block so that we are not using
methanol which can create air pockets between the slide and coverplate.
Being in Arizona our air is really dry (like the heat) so we keep a moist
paper towel close to the slides to avoid evaporation at the top of the
slides. While we still see one or two bubble ghost, it happens few and far
between and they are always small. Hope this helps. anita