The things on the hood are nozzles.
Slometimes the check valve gets clogged or gets worn. It is under the hood, in line next to the right nozzle. You may be able to clean it but if it is plugged you will probably need to replace it.
Sometimes the nozzles get plugged. You may be able to blow them out. If you use compressed air, be gentle or you will blow them apart. Blow in the same direction of usual flow.
