Windscreen wiper arm driver side fixed (rust) !!

In other words, the interior floor is wet or the water is in it. The floor is already removed and an entrance hole has already been identified and sealed. I think that the problem lies elsewhere. The hole is the execution of the spray water nozzle (as the hose) for the rear. And of course it was probably not the only one. In order to get a reasonable approach to the processes at the front of the vehicle, I would have to remove at least the windscreen wiper arm driver side. Unfortunately, it is extremely fixed. Do you have an idea how to solve it? Or do you know if the above hole leads to the processes at all? Best regards Dirk