i have a set of extractors but they get littel use. allways found by the time ive given up with my normal methods they have been ineffective as well but i can see them being usefull if you don't have as meany tools or tricks to use.
but at the end of the day heat is most effective, a Mapp gas torch will ofen do but can take a while, but the oxy spanner is king just not an ption for most