New Timer Motor 18743 kicks the unit into 'REGEN', but that's as far as it will go.

If you install a new Fleck 5600 motor timer and it does keep the time o.k. and even kicks the unit into 'REGEN',

but that's as far as it will go,

THEN:

* It is possible you have dropped the curved washer that sits behind the motor mounting plate on older models.

see:

13299 Curved Washer Older Fleck 5600

* It's job is to apply a small amount of tension to the 2 drive gears behind the motor mounting plate. The newer plates do not require the washer,

see:

http://www.softenerparts.com/Motor_Mounting_Plate_Fleck_5600_PN_13175_p/3413175.htm

* Check your plate to see if it is FLAT or "beveled". If FLAT look for the washer, or order one ( or a new metal plate ).

* If you have the newer mounting plate already, then the problem could be you do not have it securely ( or completely ) screwed down into the plastic housing ( or the plastic at one of the 2 screws is cracked ).