Thanks for your input guys, I really appreciate it. The person who bought it has never run DZ's before and I suppose he could have started / run it lean based on how he used to fly his 120AC's. However I was suprised to see all the wear at the bottom of the piston and maybe thats down to the very dusty conditions in Argentina when we flew there. So I expect I'll have to compromise and go halves on the repair bill.

Thanks once again

Keith