There are a few guides on here for rebuilding injectors if you search as well as on YouTube. There are PDF downloads of the factory manual which has the procedure, PM me and I'll get it to you.
I made a pop tester using a 10 ton hydraulic hand pump from Amazon warehouse for $48, an old injector line, a line adapter (will find thread pitch and post it), a tee, and a digital pressure gauge.
Also used an ultrasonic cleaner
You'll need a 12point 15mm deep socket unless yours have a 6 point hex head for the nozzle cap.
You'll also need a micrometer for measuring shims. It helps to have several sets of busted injectors to take shims from
Basic procedure is what I did for mine:
Clean outside of injector
Crack it open, put all parts onto a fresh clean shop towel
Check the injector body for shims
Ultrasonically clean everything
Reassemble and torque to spec, forget what it is at the moment
Pop test
Add or remove shims as needed - .001 = 55 PSI difference
Shoot for 1850-1900 PSI, ensure that your set of injectors is within 50 PSI of each other
This is a really basic write up from my.phone late at night, I could do a much more thorough post
I did all of this because I plan on running wmo and am sure to ruin some injectors
Tldr - Buy a set of injectors at russrepair.com from typ4/Russ and forget about it