The system on the sohc is very simple,
David Silver does a complete replacement master cylinder for less than £40 I seem to remember,
The caliper will possibly need a new seal,also check, and if corroded replace the caliper piston,
Also check the hoses for cracks and splits,
That covers the hydraulic section,
The only other thing is make sure the alloy arm that the caliper mounts on ,the swivel is free for it to move,
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