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Most servos come out pretty easily without any special tools.
The tool is to compress the servo spring so you can remove the snapring.
This is what the manual says........
NOTE: If tool is not available, extreme care must be taken. Spring pressure will force overdrive servo piston (7F200) assembly out of case (7005). Case bore damage may result from trying to pry on overdrive servo internal retaining ring.
Use (A) Servo Piston Remover/Replacer T92P-70023-A to compress the servo spring then remove the (B) overdrive servo retaining ring.