Yes, stock shimming is .5mm (1 x .3 alloy and 1 x .2 copper).
Check everything external to the motor. If it's been running fine it's a lot more likely to be something other than the motor. One full turn in from it's normal position doesn't sound right. Tweaking the needles by that much when it has been running ok previously may explain the flame outs etc. I think you will find it is somethng external.
All the GXII's were hauling at our 2 day event over the weekend. Making wicked power, and sounding very sharp. Tuned mine in on Friday afternoon and never touched the needles again all weekend.
It was very cool and overcast all weekend, so the engines were making lots of power, which when added to a moisture laden sticky track made for a lot of fun
Made it directly into the A final for the first time, so I didn't care what happened after that
. Just tried to keep out of the way of the gun drivers and cruised around to a 10th place finish. New 808 11 Spec and GXII-5RHO were superb, so a great weekend
.