Undo the small screw on the bottom until the lever slides out the side (no need to completely remove the screw as it engages in a slot).
The piston may catch on the cutout on the lever if it does just press the piston in with something suitably small.
Remove the piston and spring (do not lose the screw or spring
Thoroughly clean the piston and cylinder - I used a cotton bud soaked in Isopropyl alcohol.
When dry smear the inside of the cylinder and outside of the piston with a film of Araldite resin
.Do not fill
Bingo one working lift - mine did