Each variable has a Communality Index which reflects how much of the variance in that item can be accounted for by the Factors (Components) contained in your survey (here, the Likert) items.  The criterion is that each communality must be at least .30.  (The communality index is actually a percentage, so we could say that at least 30% of the variance in each item must be explained by the factors in your Likert items.)