Thanks, I was exaggerating with the soggy carpets, I have rubber mats and all is dry (at least at the moment). The lever moves just fine, it is just still that screw on the transfer box which may still be in the way.....Best of luck, get some lube on it and try moving the lever around, it should free up, sometimes the pin can cause issues, a bent nail can be effective.
And when you have removed the screws and sorted the linkage, it might be better to get some rubber mats in the footwells, the carpet has probably caused the screws to rust, by holding water around them.