Sorry can't help with the problem directly, but this may help.
We have the same problem with mine, and as we use tablets as well, have done nothing about it. We've been told that it could cost approx £60 or more to fix because it's out of warranty.
We now put the tablets in the cutlery tray, which was recommended by the makers of Finish Tablets (which we use) and the results are the same as when using the detergent door compartment.
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