They're a press fit design. Probably can't take them apart. Remove and replace with new ones I'm guessing

DON

 

The bane of diligent watchmakers. Good pushers have slots in the push piece and can be disassembled, with some care, with a screwdriver. Then if you're lucky and the gaskets aren't decomposed goop, you can service them in an orderly fashion.

To replace you need good tools to press out the old ones, a good supplier to furnish you new ones, and good tools to get the new ones in.

It's like replacing universal joints in a car driveshaft but 10 times more pain in the ass and 100 times less serious if you screw up.

 

Thanks to you both for replying. I sprayed lubricant in and around these as best I could and worked them a bit and lo and behold they started working! Now no issues - smooth operation and not difficult. Saved myself the heartache of trying to disassemble or replace.