We have been using prefer fixative on our VIP processor for three years.
We have also done a "mom" of the first three containers with warm water each
week.  The past few months we have had problems with the solenoid sticking.
Granted our VIP has some age on it but I can't help but wonder if the sticky
consistency of the Prefer has some impact on our problem.  Anyone else had
experience with this and if so do you do some other type of weekly
maintenance to prevent the solenoids from sticking.   thanks in advance,
Sheila