First off replace the spoke. If its in the rear you may have to take the Freewheel/Cassette off. Then get as close as you can in tension comparing to the spokes next to it by just using the Squeeze and Ping technique.
A spoke tension meter is a good thing to have but not absolutely necessary. A ChiCom Park knock off tension meter can be had for about 18 USD on Amazon.
For me its really not about the numbers on my spoke tension meter. Are any of these meters really calibrated and accurate? Probably not. Whats more important is they give you a fair comparison of tension related to the other spokes. If ya have one or two spokes with drastically different tension its a good indicator of a problem.
Note that I am not sure how important spoke tension and trueness is to Carbon wheels.
I am old and fat and ride slow on Ravel roads. I take time trueing my wheel sets. Each kinda has its own personality of tension and trueness.
For the most part my wheel sets are much like me, that is, more beat up than they look...
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