I have the same transmission in the shop. You don't need to pull the servo to switch the spring.
Take the snap ring off that holds the spring pushing on the servo.
Slip the stamped steel spring holder over the cast arm so it's out of the way.
Pry the end of the spring up enough to wind it out over the band apply arm.
Install the new one by winding it back in.
The new spring looks similar but is much beafier..I would switch it.
The new spring will certainly take more effort to wind in..but should not be a problem. I posted a picture so you have an idea of what I mean by "winding it out".
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