The problems you are having is why most people ditch the carrier at the first opportunity [ unless you wind down and lubricate every month ],it is also the reason you see a lot of nearly new carriers up for sale on ebay as they fail and corrode [ also been known to fail and drop on the highway ] people who have had Seval vans get wise ...!!!!!! .
With yours you now can see the problem with them, luckily you are at home , think of the problems out on the road [ usually persisting down with rain , snow and fog ...!!!] if you needed to change a flat .
In my van i bought a wheel cover [ no more getting covered in crap ] and mounted it over the wheel arch , now accessible , clean [ keep a pair of overalls tucked inside the cover and a mat ] and ready to use , and makes a horrible job easier , whilst you are at it , grease the threads on the jack as well , buy a sealey 1/2 in breaker bar and a socket and using 2 /2 in pipe clips screw it up in the corner behind the rear light access cover
, saves using the rubbish small wheel brace .
You will thank me for it ....!!!!!!!!