Hi Jim,
Thanks for the well-meant concern.
The strut is new -- never been used.  ESCO P/N 594.  No leaks.  Everything tight.  Perhaps by comments about centering were incorrect.  I'm calling Lancair to verify how things should work....  The 'shimmy' was actually was just wheel unbalance... about 1.5 oz. out.  I corrected that, tested, and it is smooth now.
Terrence
N211AL L235/320