I’ve got a dishwasher that is leaking slightly because the bottom plastic tray with the filter/motor in it isn’t attached tightly enough to the main chamber. One of the 4 screws that holds it in place feels like it will strip if I turn it any tighter and it really isn’t very tight at the moment. The rest feel normal

So, the question is can I do anything to make the screw tighter. If it were going into wood a matchstick would work but I’m not sure what I can use here. Would hard plastic glue do it for example or is that not structural enough

Fill with epoxy and let dry.

Then drill pilot hole and fit screw.

Other wise through drill and epoxy a nut on the other side of possible ?

Not a bad idea on the epoxy and pilot hole. Might try that
Can’t drill all the way through though because of where it is

You could removed the tray and apply a bead of silicon sealant before reassembling.
If needed you could break the seal in the future with a Stanley knife.

You could use a slightly bigger screw. As in fatter not longer.

Or can you drill a new hole 10mm to the side of the existing hole and so have a new fastening place?

You could use a slightly bigger screw. As in fatter not longer.

that might be possible actually. It goes into a pillar but it’s quite large

I decided against the silicone route as I don’t know how it will react to the dishwasher chemicals and I’m trying to avoid dismantling the while thing if I can just bodge it

If the “fatter” screw is too long , just cut the end off , or pack it with washers.
I’ve got loads of self tappers in the shed you could have…. 🙂