Not too many people offer to pay for advice, but that's no problem. This is a vollenteer site.
The issue with your food processor is because the cutting chamber and lid need to be correctly assembled so that the tabs on the pot and lid line up andslip into a slot in the handle. This will move the plastic peice out of the way.
A safety device to prevent putting fingers into the pot while in operation..
Watch this video and it will explain it.. about 2 mins in..