It is probably not that big of a deal. They are fairly straightforward mechanical spring-loaded tops, so just get some advice from someone who can look at it locally. SMB has 3 locations if you didn't already know, one of which may be fairly close to you, but I would say any good mechanic could understand one of these tops. If you can lift it, brace it and then remove the trim, most of which is held in place with screwed down metal snaps w/ covers, you may just find a real obvious problem yourself. It might just be a bent bar or a chain or cable out of alignment.
Also, you should refer to one of the threads/videos here on adjusting the penthouse springs to get a basic idea of what's there and how dangerous the mechanism is. I recommend a 2nd set of hands and eyes if you investigate yourself.
Larrie has an excellent video on this. Search threads by Larrie.