No tools are needed for that.
I use a small hardware bag and spent bullets as weights.
Hang the weighted bag from a shell with a strong thread,(loose you don't
want it to wrench out) this is not an exact science really,close enough works
fine you want 26,27oz or thereabouts.If your extractor comes out without
resistance you don't have enough tension.Then adjust it by placing it in a vise
with padded jaws it should be hard to bend (it is supposed to) but it is
doable just be patient.The youtube videos are a collection of balderdash.
It's your piece,you fix it.