modifying AP24

[Kigs!]

i'm trying to attatch a 1/4'' locline to distribute the flow that's coming out from a mj1200 pump, but the Y piece doesn't seem to fit into the outlet. I've seen people do it before so not sure what I'm doing wrong. The outlet of AP24seems to be composed of 2 seperate parts, and they both seem just a tad small for the 1/4'' Y piece. Any suggestions?

 

[fishes2889]

Make the hole bigger?

 

[Kigs!]

Sorry guys... really bad at DIY jobs. What tool? How would I make the hole bigger, and which hole? (the output? or the Y piece hole?) I didn't need a tool to snap the locline and the nozzles 1/4'' pieces together. They seemed to snap on with some force.