My Simpson Esprit 550 Top Loader leaked!!!?

My Simpson Esprit 550 Top Loader leaked all over my wash house floor...the interesting part is that my machine was still full of water when I found it (my dial also needs to be clicked around manually to complete the cycle). When I clicked it round to finish the cycle, I mopped up all the water from the floor and found that it didn't leak the water that was in the machine onto the floor...I checked my sink but there was definately nothing blocking it to stop the water draining as it should. I also found a small white washer looking part on the floor. I've pulled the back cover off and checked the hoses but I can't find where this washer could've come from and the hoses seem to be in good order.