The gearbox is a pretty tough unit - and the overdrive unit is also pretty robust. The only problems I'm aware of are: * the overdrive switch and relay can require cleaning or replacement, * VERY occassionally, the overdrive clutch needs replacement. I'm assuming that you're already familiar with the 940 if you own a non turbo model. You'll be delighted with the difference in performance and refinement that the turbo brings - its a huge improvement.