u/Many_Adagiow

Trying to fix this for my sister, I've seen a lot of videos where the problem is the rubber coupler disintegrating, but on hers this seems fine, and without the jug on the motor seems to work ok.

The issue is the wingnut on the base of the jug spins but does not spin the blade at all if I spin it manually, if I use my hand to spin the blade then the wingnut turns just a little. Any ideas of what I could do to fix this? I'm guessing the wingnut should spin at the same rate as the blade ie they should be connected completely?