Switch it off while trying to clear the blockage, then you could try poking a length of bendy material either down the hole from the top or up from the bottom where it opens out on to the "black bottle" - the compressor. I have used wire, but the plastic stuff used in garden strimmers might also work. Once you have got a way through you could give it a dose of dishwasher powder to remove more of the gunge...
Finally, clean up the top of the compressor and switch it back on again!
Friend, November 2007