halacha - What happens if a sefer torah might have a mistake?

If a sefer torah has a definite mistake, it cannot be used, and the reading must be done again from a kosher torah. (SA OC 143:4)

But what if it only might have a mistake? For example, if it's unclear whether a letter is a ו or a י.

Does the reading continue (we're lenient), get stopped and replace the torah (strict), or perhaps something else?