How to replace the convertible top cylinder?

Not sure, but I bought it with to being open as one of the strikers was broken by the windshield. So, I replaced it and now top closes but who knows what previous people did, just strange I fixed many tops not sure what makes the rear tight enough for the shield to look flush.

Is it possible someone replaced the top vinyl but did something wrong? The top looks great with no tears and it is hard to believe its original. Thats only thing I can think of.