It looks like the gray hose has a lip on it that is supposed to be captured by that white "collar" or union nut that screws into the rest of the PVC piping.
Ideally in that sort of setup you could unscrew the white union nut and slide it up the gray discharge hose without any issues. Try unscrewing the union nut and look at how it's supposed to interact with the hose and the rest of the piping, that should give you a better idea of what needs to happen next.