Dishwasher model FFBD2406NS0A in this example - when you look it up the rinse agent is sold complete and you cannot buy the cap separately. This rinse agent/soap dispenser is 15480101 subs to 5304506521 and list pricing is $71.35 Pretty pricey if all you need is the cap. We took a chance and ordered 154388801 cap at $20.00 - other than being white it fit just fine.

Thought we should share this information since it took some research to get to this point.

However if your cap will not fit tight in the rinse agent dispenser, it may be the dispenser itself is needed. Now you have options.