ASKO dishwasher, various draining problems

We have a 10 year old ASKO DW, and we mostly love it. It has recently developed a problem draining, and I discovered that the inlet valve/ solenoid had a slow drip. I replaced that, and the problem was reduced, but not eliminated. What happens is that water builds up in the bottom catch pan, and then triggers the float which prevents the unit from filling.
I cleared the pan, and ran a cycle. Perfect. I ran another cycle. This time when it had finished, there was water left inside the DW, in the bottom, but the dishes were clean. I ran the cycle again, and the water from the bottom of the DW ran through the overflow into the bottom pan, again triggering the float. Ok, that's why is shuts off, but my question is:
What would cause the DW to not pump out all it's water sometimes?
Other info: The DW has a electro-mechanical rotary controller, no fancy electronics. The drain is looped up and then down. No vacuum break has been installed. The original installation instructions did not call for one, but later installation instructions did! Note that the drain hose runs from the pump, up to the plastic hook, then down through the floor at the back of the cabinet into a 2" ABS pipe, trap, horizontal run of 2", (total 15') then into a vertical 2" pipe, into the basement floor. This final drop appears to be correctly vented, but I haven't tested it.
Some previous posts indicated that a slow drain might cause an overflow. I'll try to put a fish tape down the drain to see if it is clear. What specifically does the 'vacuum break' do, and how might it affect my installation?
Thanks for your help! Rob
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Your Asko DW lasted 10 years? That is amazing. After 4 different things broke on ours during the first 3 years we dumped it.

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I have had similar drainage problems with my ASKO twice in the last 6 months and I cannot see what is wrong with my drain either. I'd love to hear from someone out there on how to cure this permanently. Taking the tray off and sponging out every 3 months does not appeal.
Thanks mj
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On Oct 14, 11:17 am, snipped-for-privacy@gmail.com wrote:

Hi Martin
I'm the OP
Could you describe your drain connection in detail? Mine is unusual, so I have always wondered if I caused the problem.
Two other questions: 1) do you have a vacuum relief valve on the standpipe, or do you drain into the sink drain? 2) I have noticed recently that the left 'rail' that supports the upper dish tray has worn out. It runs on ball bearings (4) and I think that 3 of them may have been lost in the machine, plus there is some thin plastic missing as well. I'll replace this support, IFF I can figure out why it is overflowing. I've read about similar problems with other ASKO's clogging the drain, but I didn't pay too much attention before I saw that my rack was failing.
My ORIGINAL problem was a slow leak/drip from the inlet valve. Put a small dish under the valve run the dw for a week or so, then check to see if the dish has water in it. New valves are < $100 and easy to replace. (2 wires, a hose clamp and a threaded fitting)
Have you disassembled the drain/pump? What did you do?
Good Luck Rob
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