I have exactly the same problem on the same model (Ariston A1636). It happens at the end of the rinse cycle. The machine starts spinning (clockwise) at the end of the rinse, and the drawer being at the top left, the water goes straight back up and out the front. When draining, I can hear water flowing out in the drain, but obviously not enough, as it shouldn't spin with lots of water still in the drum. I'll check the pump and hoses.
(Called the customer line, which in fact is a sales desk offering 1 off visits for about £90 or about £140 for 1 year maintenance. No advice whatsoever on fixing it yourself. Disappointing, but then again, I don't know if other manufacturers are any better.)
Thierry S
July 2006