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New Member, from California
E-mail me at firstname.lastname@example.org and I'll be blad to help.
Let me know if you still need some help.
Sorry that it took me a while to see that you asked the question.
If your unit is older or on water that has high hardness or high iron the seals in the piston cage can get stiff and might make a grove in the piston or hold the piston up from moving from front to back an back to front..