Jack Rabbit Shock Problems

[Bunglefuzz]

Help please, this is driving me bonkers.....

Been trying to set up my newly aquired Jack Rabbit.

The front suspension was a bit stiff, so checked the mechanism with shocks disconnected, which all seemed fine..... So started to dismantle one of the shocks, poured the the oil away and now the piston won't go up and down at all smoothly when it's screwed back in. On it's own without the resevoir/sleeve it slides fine.
So I tried filling it with oil, but then the piston doesn't move at all, so much so that I can't even screw the piston assembly in fully. Most shocks have expansion chambers to allow for the volumetric size of the piston rod.
Question. How best to rebuild these shocks?

I once had the exact same problem rebuilding an Ayk Viper's shock, what the heck am I doing wrong? These shocks should damper like a hot knife through butter, yet it feels more like I'm trying to flush a house brick down my toilet.

Basically, it slides fine without the sleeve, but once added, even dry, it locks and is really rough and notchy.

Many thanks....