Hi, I see you are new to the Brickboard welcome aboard.

I have been a 240 man since 1978GT that was our first passenger car.
I have only seen that wheel on rare occasions in the JY.

I believe that the wheel is larger is overall size or diameter than steering wheel before and after your year.
I’m guessing that some cars came without the power steering option or even air conditioning.
Sweden is a cooler place with is mountains and moose.

So it was the standard wheel used on sedans until about 1986.
I got my 1984 way after the 1986 wagon and learning this was unintentionally backwards for me. Sometimes I think it’s my Method Of Operation by nature.

Nowadays they use a big horn pad in the center. Not everyone drives with both hands on the wheel @ the 2&4 o’clock positions.
My station wagon came with the smaller wheel that was standard on my GT.
The 1984’s bigger wheel made me feel like I was driving an old 1954 Dodge or something.

Your photo jogged my memory and I went and found It.
I kept the other one so the car will be as original if a future owner wants to make it so.
My 1984 still has beauty rings and center hubs for the tire rims too.
It’s easy to spot it like my GT “HAD” stripes that definitely dated the car.
When the clear coat up and flaked off, so, did the stripes.
The car was a long ways from being a race vehicle.

From looking at the wheel and knowing how they pull off like the center pad does.
It’s my guess is the button will pull loose by using a flat type hook arrangement from around under the sides.
The center pad, as I remember clips on to the insides of the springs.
I do not see screws in the backside to release anything from the front.
I would pry with anything that put a narrow edge of force onto an edge of plastic of this age.
No one knows how much sun or hand lotion, has gotten onto the buttons.
Something as wide as a popsicle stick but a lot thinner should be able to sneak down in there and feel posts. You want to be as near to them as you can feel out.
It doesn’t take much to hold the buttons on, as any effort to use them, is inwards to blow the horn.

I imagine the center Volvo emblem just pops in as well.

Good luck with working up a fix. Post back what you found to be the problem that DAD fixed.

Phil