This model has been discontinued. 
Very few parts are still available.

For parts, Go To:

http://softenerparts.zoovy.com/category/1100.fleck_parts_numeric/

* Copy of Fleck 3600 Owners Manual available for $ 10.00 *

 Please contact us with your need and we will let you know what can be done.
The replacement for standard residential use is the Fleck 5600 valve.
 For Hot water applications, the new Fleck 4650 is available as a special order.