Never mind guys, I found the problem: I installed the piston seal the wrong way... Doooh :-( I don't know if this has happened to others, I feel stupid enough, regardless.
The seal was tight up against the bottom of the compression tube - it was also a nice play to get that seal out from there )a 1-2Á dowel and a piece of a straightened coathanger wire with a 90 degree sharpened/flattened bend at the end did the trick.
And now, onto the new seal.
Any tips where to order from?
Thanks in advance,

Las