toilet 2-button flush

[thelma]

Hi
it doesn't matter where I press the button, I can't tell the difference in the amount of water. Is it working correctly ?
Thelma

 

[digdilem]

Try it with the lid of the cistern off. (The ones I've seen, the central bit around the buttons unscrews with finger pressure)

Inside there'll be a tube with two levers, watch the water level and press one. Let it refill and press the other. If they're the same, my guess is something has broken. If they're different with that, but the same with the lid on, probably the button rods are pushing both levers, have got stuck together or misaligned somehow.