All I can think of is keep turning the wheels until the clicking starts or stops depending on which one is the problem. And be patient. Don’t rush it.

Are you telling us the lock refuses to unlock?

For future readers of the question’s detail part :
“If the wheels come off (because no clicking, too much oil maybe?), how do you make it click, i.e lock?”
@TJFKAJ (I guess you got the question anyway. )That would make sense and it has been tried, lots and lof times.

I have no idea what you are asking.

What is the object that is not working? What oil are you referring to?

The wheels fall off the case? What has that to do with the lock?

Wash off the oil with Brake Kleen. It comes in a spray can. You can find it in auto parts stores.

I second @kritiper ‘s suggestion. I would also try blowing compressed air at it o blow the oil and Brake Kleen off. Carburetor cleaner would work, too.

You guys understand this?

And if she’s talking about plastic wheels on a rolling suitcase (which is what came to my mind), I would be careful about recommending anything beyond finding someone to look at the thing to understand what she is talking about. I mean does “the wheels stay on” mean they are free to turn?

@stanleybmanly Punctuation and a better description would help but my answer was mostly how to remove excess oil. And it has the side benefit of cleaning the part or or mechanism if there is is rust. (I imagined something like shopping cart wheels or the ratchet mechanism from strap tie downs.)
I either use my air compressor for big jobs or small cans of compressed air from Walmart for $4 per can.
Of course, you need to spray it outdoors so you don’t spread oil all over your kitchen wall and floor. (I might know this from experience.)

What item are you referring to @flo?

Thanks @kritiper and @LuckyGuy.

I guess the clicking sound is the indication that the locking feature is not working, not that the no clicking sound caused the locking feature not to work. Some wheel chairs have this feature…

I’m asking anyone who possibly understands this to attempt an explanation. PLEASE!!

I wonder why it’s not every every wheeled item that has this feature.

I don’t know about any locking feature unless the wheels have some form of Sprague Clutch. (A clutch that looks about like a roller bearing but can only turn in one direction.) I’ve heard wheels with clicking noises but the noises were just the ball bearings striking one another as the wheel(s) rotated. If a wheel is like this and locks, it may not be designed to, and may have some small gravel in the works.

I have nothing to post about that @kritiper I’m not at informed about it.

Let me just correct? myself re. my last post. There is the locking the wheels in wheelchairs, so wheelchair doesn’t move, and then there is locking in the wheels so they don’t fall off the frame of a personal shopping cart for example. So, different things, right? My question, OP, is not about the brakes on wheelchairs. Sorry.

On shopping carts, the answer might be self locking nuts.
On wheel chairs, it is a foot operated gizmo that squeezes the wheel to keep it from turning.

Ratchet strap ? ?

For hold down maybe?

This pulling of teeth is laborious, but it appears the question is more about how the wheel assemblies are secured to whichever platform flow has in mind. This business about brakes, locks, clicking and excess oil somehow facilitating the detachment of the wheels remains a puzzle. Can anyone nail this down? @flo, would you please indulge us one more time? The lock is as @kritiper says. Those chairs aren’t usually equipped with what would pass for brakes. And the only lock on a shopping cart is usually the one triggered automatically to prevent one wheel from rolling freely if the cart is removed beyond a predetermined distance from the store.

Is this what you are talking about?

EZ Lock