Rampage xt throttle servo

[Bigtoys1]

Hello all I am new to the r/c hobby world and could use some advice. I’ve read where the throttle servo can become unresponsive and would like to change it to something a little more dependable. Can anyone tell me what I need to do in order to get the car to start without me pulling the pull cord for 30 minutes to get it to start but once it’s started it’s good starts right up after it’s warmed up . Like I say I’m new to this and could really use some direction thanks in advance