ZYMATIC STEPPER MOTOR FAILURE
If you have ever received the stepper motor failure error, chances are you have a failing stepper arm seal and the unit needs to be dismantled and cleaned. Sticky wort will leak out of the top of the stepper arm, due to the way it is designed, and this will gum up the internal workings of the arm.
You'll need a 1.5 mm allen wrench, 9 mm hex socket, at least a 15 inch socket extension, a #2 phillips screwdriver and a #1 phillips screwdriver. Its also wise to have a sharpie on hand to mark the stepper motor and the stepper arm.
I usually remove the top of my Zymatic about every three months and perform a QA check to make sure my seal is intact and no leaks are evident. However, I have been brewing a lot lately and last brew session received the error. With the machine off, I manually tried to move the stepper arm and noticed it was frozen solid. That's a good indicator that I had a leak and gummed up the assembly.
Upon removing the top cover of the Zymatic this is what I found.
That's about normal for what I have seen in the past, so it was time to break it down, clean the assembly, relube everything and get back to brewing.
I clean all the individual parts in hot soapy water (not the optic sensor) and I soak the two stainless steel tubes in PBW for about 20 minutes. Then I run a pipe cleaner down both tubes and clean out all of the junk. You'd be surprised what accumulates in those tubes.
All back together and in the home position ready for installation. You'll need to make sure that you use plenty of keg lube on the stepper arm seal that mates the two SS pipes together. This is the wear point in that assembly and the reason that this assembly leaks and causes errors.
I always take this opportunity to align my stepper arm at the home position and the bypass position. Doing this ensures all of the other adjunct positions will align correctly. I make sure my stepper arm is directly in the middle of both the home and bypass holes in my Step Filter cover, after reassembley. It's easily adjusted with the top off if you are slightly off.