Now that you have the Trout Yogurt Dispenser, you should probably go find that maid who asked you about it outside of Jackie's Cafe earlier. But first, the monkey from the monkey cave has something very special (and extremely helpful) to teach you.
Follow the monkey down to the roadway. It will ask you to watch as it uses PSI Teleport. And then, it will pass that knowledge onto Ness! After the monkey observes your test run (in which you need to make sure not to crash into anything,) you'll end up back in the desert, and the monkey will head back to the monkey cave.
PSI Teleport is great. You can use it to teleport to any location that you have visited before. That means that you can go to Winters now! And you should, because the store next to the boarding school has some good upgrades that you should try to get.
Meet Electra at the Monotoli Building
Once you're done Teleporting around the land, go to Fourside and head to the Monotoli building. Electra, the maid, will be hanging out nearby. She'll see you and, in her excitement, will take the Trout Yogurt Machine off of your hands, before dashing into the Monotoli building. Before she goes in, she'll tell you to come up and visit her on the (previously restricted) 48th floor.
Go on in, but keep in mind that the 48th floor is full of sentry robots that will attack you on sight. After you take the normal elevator to the 47th floor, go across from it to use the private elevator up to the 48th floor.
Fight through the 48th Floor
As soon as you step out of the elevator, a Sentry Robot will approach and attack you. You can just use physical attacks to get rid of it, although if you end up fighting more than one in the same battle, you might want to use PSI Rockin to make the battle shorter. Rust Promoters are helpful against these metallic enemies.
The quickest way through is to go into the door to the left of the men's bathroom that you pass by early on, then go through the door at the top of this room with four desks. Next, in the room with two desks, use the door on the left. From here, there are two doors at the top of the room, and you should go through the one on the right. Finally, go through the door on the left.
In here, you'll encounter the Clumsy Robot. Once it's gone, you can go into Monotoli's private office.