Scarab master cylinder stuck piston

[Mick b]

Hi,
Just received my Scarab master cylinder and thought I'd see if the piston was free or not. After a gentle squeeze it moved all the way in. Good news I said to myself, I'll remove the lever, get the air line and that will be job done. However it was not to be, sustained pressure (130psi) did not move the piston out at all.

I'm about to try and persuade it out using a grease gun and a suitable nipple. Is there anything that I am missing or unaware of before I start.

Thanks in advance

Mick