I cant say for sure if the G152/G154 ( Iseki TX1300) seal is the same as the G172/G174 seal but I would bet my last dollar that the G172 ( 2 wheel drive) and G174 (FWD) use the same seal. Here is a link to another forum discussing a G174 3 point lift issue. The OP says the G174 ( iseki TX1500) and the Iseki TX2160 share a lot of crossover parts.
https://www.tractorforum.com/threads/bolens-g174-hydraulic-lift-problem.24600/ A little more searching indicates the White Field Boss 16 appears to share a lot of parts with those Iseki and Bolens models. White Field Boss 16 parts diagrams and part numbers are available to view at
https://apb.agcocorp.com/ -- enter site as "Guest User". (You may or may not be able to view this site since you are in the UK)
Here are part numbers for the 3 seals on the FB16's 3 point piston.
33-0129011 1 RING - BACK-UP
33-0128872 1 O-RING
33-0042331 1 O-RING
Who knows if any of this will match your TX, I'm just try to give you some options.