AEG washer/dryer tiny leak from humidity sensor

AEG L7WEG851R washer/dryer. This is about the third issue I've posted about for this machine; it hasn't served us well!

I have checked advice articles and can't find anything about this specific issue.

Background

We discovered recently that the water was not actually getting hot, so I got busy with my multimeter and established that the heating element had no continuity. I've fitted a new one today and it's working - the water is hot.

However during my testing I also removed what I think must be the humidity sensor, presumably for when it's drying. It goes into the back of the drum and has a probe on the end. Please correct me if this assumption is wrong. I've attached a couple of photos to show the part I mean.

Issue

When trying to reinstall the sensor, it doesn't feel like it's going in as far as it should. There is a rubber grommet around it with a little flange, which feels like it should locate into the hole in the back of the drum. However it doesn't go in very far, and the grommet seems like it's way too big to go in there.

Since replacing the element, I've run the machine and all seemed well. However I took the cover off the back again to check all was dry inside, and there was a bit of water in the void just below the humidity sensor.

I'm guessing this can't be right, but I also can't see how the sensor can go in any further.

Any advice on what I should do?

Photos - one shows the location of the sensor on the back of the drum. The second shows it closer up, with an arrow where I found water had collected.