I've brought the 'van out of storage today and found the roof vents full of dirt and grime. The worst one being the over shower one that "pops" up. I'd really like to take down in order to clean properly. Can I take out the 4 mounting screws without the whole thing falling to bits?. Also broke the battery strap bracket inside the battery box too. Are these available from a good accesory store? Other than a good scrub down, we are ready to start the new season. Happy caravanning season to all.