The top drawer spray arm is driven from plastic tubing running from the base to the top of the machine, on the back wall. This has two holes in the middle. There’s a clip-on bit of plastic over this. When you push the top drawer right in, the water tube for the spray arm under the drawer slots through the clip-on plastic, into the holes in the main distribution arm.
There was clearly some sort of seal/gasket/washer on the ‘clip-on’ bit of plastic. Thus the top drawer slides though this and the water gets delivered to the spray arm, rather than just running down the back of the machine.
But this seal or whatever has perished. It’s now crumbly, but I’m not sure what it was? It’s white, plastic-y feeling. Should I just replace with some sort of washer? Or can I buy replacements of the proper items, or of the clip-on plastic part at the back?