Range Rover Master cylinder -how to dismantle

I have a 1989 Ranger Rover classic 3.5 without ABS.
Proplem started by renewing all brake pipes then found could not get brake fluid to flow from master cylinder reservoir to primary pipe circuit

Have now taken off master cylinder from servo etc and removed the yellow plastic transfer housing cover.

Next stage how do you remove the primary plunger assembly from the master cylinder body ? Cannot see any circlip !!

If this is easy, is it worth buying the repair kit or replace the complete master cylinder ?

Any assistance most appreciated

Normally, the circlip is located under the rubber boot that the operating push rod passes through. Remove the clip and carefully remove the internal piston and valve assembly..lay it out in exactly the order it comes out. You should be able to get an overhaul kit comprising seals etc.
Reassembly is reverse operation.
Clean the parts with Methylated Spirit and lubricate with clean brake fluid before re-assembly.