I had Hal Stockman R & R mine (for the first time) at 1,300 hours. He replaced the Belview (large spring) washers and re-shimmed as req'd. The only wear was about .010" on the Belview washers which was 'normal'. All for about $200 and quick turn around. Thank you, Hal! In my opinion, some of the Rotax intervals are way conservative with the exception of oil changes. I do 50 hrs. and run 99.9 MOGAS.