Thanks for the replies.
I will look into it this weekend. It is quite hot here in South Africa as it is summer.So weather will help with a quick dry.
Will get my spotlight out while the covers are off and have a peek inside these vents then to see if I cannot see rust and stuff that has already formed. Hopefully I am lucky and it will only have minor rust.
Will try and get a brush in there aswell to rinse and brush at the same time to get everything out.
Will also look into that drain hole story to see if it is not clogged.