Not necessarily, assuming they're correct and it's slipping internally, like they've actually watched it slip, then things can be worse in the smallest/biggest cog if there's a bit of play in the whole assembly and force on the outside pulls things out of line slightly. It wouldn't be the first thing I'd look at, only after ruling out worn teeth. I'd still just buy a new cheap one though.
Not necessarily, assuming they're correct and it's slipping internally, like they've actually watched it slip, then things can be worse in the smallest/biggest cog if there's a bit of play in the whole assembly and force on the outside pulls things out of line slightly. It wouldn't be the first thing I'd look at, only after ruling out worn teeth. I'd still just buy a new cheap one though.