I purchased a Ferris Z3 yesterday after having done demos on a Toro Grandstand and a Ferris Z2 and loved them. However with my Z3 I am getting pretty bad back pain which I didn't get with the demos. Is there a way to adjust the spring that holds the platform? It seems very stiff in my opinion. I did put the pin In the same hole on the bracket connecting the shock to the platform as I had on the demo units. I had heard you could adjust the shocks on the IS models so I hope there is something on here also.