The issue isn't necessarily getting or making a tap, but picking up a good lead. Often when dealing with damaged or crossed threads it's hard to get the tap started straight as it will want to pick up the crooked lead of the first thread and extend it. That's why it's good practice to remove or open up the first thread, or in the case of a through hole like a crank arm, to tap from the opposite side so the tap moves from good thread to bad.
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