Velux windows: seal has gone?

We moved into a place with 2 velux skylights. We've tried to clean them but it seems as if the dirt is stuck inside the window (between panes). After contacting velux directly they say we have to replace the entire window - seems excessive and not sustainable? I assume we could at a minimum at least just replace the glass or is it possible to even remove glass, clean and then reseal? Any advise appreciated!