to examine (a thing) carefully in order to learn something about it

examine and determine

to remove faults, problems from a computer or a computer program

troubleshoot

to cause (something) to become free from complications or confusion

unwind, disconnect; solve

to identify, state, a difference between people, things (by looking, listening, thinking etc)

tell the difference

to make (something) more efficient (by getting rid of slow or wasteful methods etc)

arrange, organize

(to cause threads) to become separate; to solve (a mystery)

solve