Bob,  On second look I could not find the reference I recalled.  It must be in
the builder's manual.  It warns us to do monthly emergency gear extensions to
make sure the strut is doing its job.  If the gear should fail to come down,
we are to replace the gas strut.  I don't remember the speed called out, but
you can pick the 87 knots the POH says or a higher number.  Or do it at 120
knots and slow the airplane, recording what airspeed the gear locks.  When
that airspeed deteriorates to 87 knots, it's time to replace the strut.

Regards,
Ed.