Home inspection?

We are a first time home buyer. Recently we did home inspection. Found some problems like high amount of carbonmonoxide when the oven is turned on.Seller says he will fix the problem.Also gutter needed cleaning.So my question is how can we believe that seller has fixed the problems,since we don't have carbon monoxide detector or we don't know how to check the gutter.Need some advice on this please.Or do you guys suggest us to do reinspection only for this?