What should a magiah need to fix when checking? Only the matters which are posul and other fixes like hosafas dio when very necessary? Or one should fix even smaller problems including but not limited to missing tagim of Bedek Chayah and shatnaz gatz (how about on the back of the mezuza where it is not at all meakev? I see that many are not makpid on adding tagim on the back, not that is a proof that it should not be the Magiahs obligation to fix it if he is anyways checking it, however it is not so simple to obligate fixing in the back either).
Two things to keep in mind:
1)The more the unnecessary fixing the higher chances there are to also potentially posul chas veshalom.
2) When the client gives their sta"m to be checked are they not expecting that even smaller issues should be fixed. (Is that not what they are paying for)?
I know that not all magihim work the same, is there a oral or written teshuva to this question?
I however think that it also depends on the general status of the sta"m (i.e. higher quality sta"M we are quicker to make fixes than we would if it was cheaper quality sta"M.