My hotpoint aquarius df61 do not clean properly cannot find the problem all filters cleaned .all of the crockery comes out dirty

Just had same problem. Checked and cleaned spray arms filter and impellor. Still had problem. Noticed that it appeared to be expeling water to drain at wrong time. Openned mid cycle and noticed water level low.
Took off left side panel to reveal pipework. Main pipe route big oblong in clear plastic had a red valve at the top which was gunged. This was the air release so when water is pumped in air has nowhere to go so it pushes water out through the waste so ther is too little water in machine. Removed this component and used caustic soda to dissolve food waste blocking valve as there is no access. Put it back together and now it works fine. Took about 2 hours (1 hour for caustic to work) no special tools other than star screwdriver required as it all unclips.