It might be hose trouble or alternatively (more common) is a blockage in the drawer or the drawer housing, this is especially more likely if you use detergent powder.
The drawer should be removed and washed periodically and the inside of the housing examined to ensure it is clean and the outlets are clear.
If you don't find a problem it will be necessary to take a look inside the machine at the hoses.
Answers & Comments
It might be hose trouble or alternatively (more common) is a blockage in the drawer or the drawer housing, this is especially more likely if you use detergent powder.
The drawer should be removed and washed periodically and the inside of the housing examined to ensure it is clean and the outlets are clear.
If you don't find a problem it will be necessary to take a look inside the machine at the hoses.