Zanussi ZDT12011FA – Water pumping into base and flooding

Hi, hoping somebody can help me. Dishwasher been out of action for a while now – it stops a few minutes after starting a cycle with 3 beeps intermittently, signalling that the anti-flood sensor has kicked in. I took the front panel off (the dishwasher is integrated so this is the most access I can get to the underneath of the machine) and the base was full of water. I manually drained/soaked up all the water and tried running a cycle again with the front panel off so I could see what was happening underneath. A minute or two after starting the cycle, water starts pouring out of a small pipe (around the diameter of a 5p coin) that seems to be attached to the pump/motor in the centre of the base of the machine. The water continues to be pumped in until there is enough in the base to raise the float and activate the anti-flood sensor, causing the cycle to end. There doesn’t seem to be any loose parts in the base that may have fallen off the end of the little pipe, so I am assuming it is designed to be open this way. I have tried the following to resolve the issue:

[*]Checked any filters inside the machine – no food appears to be clogging it that I can see
[*]Removed any kinks/twists in the drain hose
[*]Ensured the drain hose has as high a loop as possible underneath the sink

I removed one end of the drain hose (the end under the sink) and sucked on it; I could hear the water being sucked from somewhere inside the machine and was able to get some water to pour out the end of the drain hose – does this mean that it isn’t blocked if water is able to move through it?

This is starting to drive me insane. Any advice/guidance would be massively appreciated!

Thanks.