I have an interesting query - which may become a reality if a particular sefer torah comes my way.
Some synagogues, if they have a seam split between yeriot will repair them themselves. Sometimes they may not use giddin - in which case obviously this has to be changed. Sometimes however they will use giddin. In which case that should be fine.
However not all members of a synagogue will be shomer and it may be that the 'handy-person' who made the repair was not shomer. If the sofer receives such a torah and is not aware of who made the repair and even where the repair is - do they assume that b'dieved all is well and the sefer is kasher. One wouldn't expect to restitch the whole Torah. Now what happens if the sofer knows for sure that the person is not shomer. Is the sefer kasher or does all the stitching have to be removed. Or is this similar to the story where a sofer said they didn't sanctify Hashem's names to the person who commisioned the Torah because they fell out with them and that a) the sofer only gets paid for writing a chumash, but b) the sefer is held to be kasher as we do not rely on the admission of the sofer. Or is this perhaps equivalent to the case if the stitching repair was made by a women in that community - where the preference in the halacha is to undo the stitching but the halacha is that it is okay after the event (Mishnat Hasofer) and it is fine b'dieved.