mpcguy wrote:
i have an 09 ai with turbo st fins. i'm having an occasional problem with pedal adjustment skipping to the next hole on the adjuster when pedaling with reasonable effort. has anyone else experienced this trouble on a late model mirage drive?
Yes. I changed pedal positions once and forgot to make sure the pin was fully engaged. This resulted in sheering material off the drum and eventual drum failure. Whoops! 
Here are some things to check out:
1. Matt mentioned the possibility of a warped drum. Inspect the gap between the crank arm and the drum main body (where the pin inserts). It should normally be 0 to 1/16". If more, this could indicate a warped drum, preventing full pin engagement.
2. Inspect your drums to see if there is any chipping or missing material in front of the usual pin hole (see pic above). If so, you can reverse your drums and get fresh holes.
3. Make sure your pins snap in smartly and are fully engaged (procedural precaution).
4. When pedaling look at your crank arms and see if either one is pulling away from its drum during the push stroke. This would indicate a possible hairline crack in the crank arm and could be responsible for excessive flexing (pulling the pin away from the drum).
5. Make sure you have the v-2 drums (they look like Mickey Mouse ears). The older drums were more likely to behave as you described.
