I am changing the convertible top on my 1969. All of the rivets are good and tight except for the two holding on the rear bow, which are pretty loose. Is there anything I can do with these short of spending $75 for a new set of rivets, most of which I won't need? I can't find anyone who sells single rivets. How bad is it to leave it loose? It doesn't look like it's coming off. Thanks.