Dishlex Global 300 won't drain

Question

This d/w is about three years old. No problems with it so far. Recently though, the clean is not very good. Residues are left on the dishes and it won't drain.

I've got the arm and filter removed, however there's a pool of water in the cavity in the floor of the d/w. I could drain this using a pump, but how do I get rid of the blockage (if that's what it is) leading into the drainpipe?