I have a Stihl MS 170 that is about 4 years old, with very little useage. Recently the hooked end of the throttle linkage started popping out of the slotted lever on the carburator. I have reconnected it twice and it just popped out again. I don't see any retainers or anything to keep this linkage captured. I thought I would just bend the open slot closed on the carb lever, but that metal is very hard and would probably break before it bent. How can I prevent this rod from coming loose? Does anyone have a diagram of this linkage, or a PDF service manual?