Seal & Spacer Kit 60121 for Main Piston used on Older Fleck 1500, and 2500.
Also used on newer 2510, 2700, 2750, and 2900 upper piston.

NOTE: The Seals and Spacers need replacing when you have "internal" leaking of the Valve.
This would be constant flow out the drain line, or failure to create suction ( after injector and brine valve check out okay ), or hard water getting into the house when everything else appears to be working fine.
If the Valve is Leaking from the Front of the Main Piston, you Must Replace the Main Piston Assembly to stop this type of EXTERNAL Leak.

NOTE: It is difficult sometimes to get all the old seals and spacers out, and it's almost impossible to put them back in without the special "stuffer" tool.
The stuffer tool includes directions for it's use.