Hi Graham,
If it is lower at the front of the frame tubes maybe the fork springs are the problem. Mine came out in many pieces when I stripped the forks, a common thing apparently. Got new springs from club spares.
I measured the height to the centreline of the torsion bar at the front and it is 230mm. Distance from ground to centreline of the leading link pivot point, the chrome cover, is 310mm.
Regards
Clinton