How can I stop my Miele Novotronic from jolting when spinning?

In the past 2 years ( our machine is now 11 years old), our Miele Novotronic has started to jolt/vibrate sometimes when spinning mid wash. We have had some of the electronics replaced but the machine still does it from time to time. It only seems to happen when washing towels resulting in us having to split the loads to rinse and spin. Why would this be the case now and not before ? Should we be thinking of replacing the machine?

Sara
May 2009