I was hoping that someone else would reply but it looks like no one will.

I do not for a fact have an answer.
I would suggest that you contact GE.

Looking at the picture I see the metal part has 3 little nubs on it.
Look for corresponding marks on the tub ceiling.
My thought here is that it may have been spot welded.

If it was spot welded the only way to fix it (at least officially) is to replace the tub. This really is not practical so I would resort to a jiggery pokery method.

Get a couple stainless steel screws.
Self taps would be the best if you can find them.
They do not have to be very big just long enough to go through the hub and bite reliably into the tub ceiling.
Remove the hub and drill a couple holes in it just large enough for the screws to fit. 2 holes should work but 3 would hold the hub better.
Place the hub on the ceiling and then mark where the holes in the hub are.
Then drill these with a smaller drill (pilot holes).
Now just screw the hub into place.
I would put some RTV sealant onto the holes/hub/screws before installing. This sealant is usually heat and solvent resistance and should to a good job sealing the holes etc.

Stainless bolts and nuts would do a better job but you would have to pull the dishwasher to do this.
With screws you should be able to do it without pulling the dishwasher as long as the screws are not too long and you do not drill inti the bottom of the counter top.

I hope the above is of some use to you.
I have never done this but am confident that it should work.