We have had Dako autostainers for about two years and
do run two and three runs a day.  We have had some
problems with variation in staining but have not had
them since 1.  the machines were leveled and we put
pads under the feet to stop the machines moving from
vibrations. 2.  we received the new reinforced racks
that don't bow over time. 3.  we clean the machine
after every 150 slides and we clean the probe with 95%
alcohol.  If you are using AEC this is a must.  4.  We
change the tubing coming into the machine at least
every six months.  Our water is not good and grows
icky stuff if we are not careful which can interfer
with even staining.  5.  Also we add 6.0ml of Tween 20
for each 10 liters of buffer.  6.  We additionally
presoak slides at least five minutes in buffer before
we start our runs.  7.  Lastly, we redefined the drop
zones.

If you want to check your instrument for the amount
being placed on each slide, put 48 slides on the
machine and  0.4 ml of a colored solution in each tube
(this would be your Primary locations only) and start
the machine and do a blank run.  In the end, you
should have, say 200 microliters left if you directed
the machine to add 200 microliters.  You can also
watch and see just how the reagents are covering each
slide.  

Hope this helps....once again we love our Dakos (total
three) and with a little attention, you can find the
cause of your problems.  All machines have little
things that go bump in the night.  Good luck.

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