Seal replacement procedure
Unscrew the top endcap (be aware of spring forces inside the cap)
Make a note of the number and configuration of the disc springs inside the endcap and remove the disc springs.
Remove the small setscrew that holds the reaction nut to the puller bar and unscrew the reaction nut.
Remove the bridge component by unscrewing the small setscrews. Be aware of the internal spring.
Withdraw the puller bar from the load cell.
Remove the four socket head cap screws that hold the manifold block in place, remove the manifold block (there are two small seals between the manifold and load cells, keep safe for latter replacement)
Unscrew the two load cells apart, if multiple tensioners are being dis-assembled at the same time it is extremely important that pairs of load cells are kept together and are eventually re-assembled together. Load cells are matched pairs.
Using a soft material dowel, tap the Pistons out of the load cell bodies, Tap from the underside of the load cell through the bore.
It is recommended that all Seals be replaced at this time not just the failed Seal.
Using a small flat blade screwdriver prise out the seals and anti-extrusion rings from the two load cell bodies and the two pistons. Discard these seals.