Thanks to all,
I now fully understand the purpose of the spring, not only for chain saw use but also
for anti-vibration.
Yes, the strain to the servo can be reduced by changing the servo horn angle to the
linkage, and less strain at full angle position.
I will leave the spring on the carb. All of your comments helped me very much.
The word " with that spring off the stopper" at my first question meant "unhooked".
Thank you again.

Tsutomu Mabuchi