Hi, we have a push button toilet which has just started to fill really slowly. Inside, there looks like there's a plastic arm with one end stopping a jet of water and the other end pivoting on the float. The end that stops the jet of water is hissing water out of the top whilst there's just a trickle coming out below (can't see where from). I'm assuming that the little jet of water that's hissing isn't the water that actually fills the cistern - only because there doesn't seem to be enough of it coming out to have filled the tank so quickly previously, but might well be wrong.
Has anyone got any ideas as to how to fix this?
Any feedback would be gratefully appreciated, it's getting hard for everyone to stagger their bathroom breaks 2 hours apart!

We had a similar problem, but because my mum dealt with it, I am not 100% sure what the problem was. We had a plumber come round and he was able to adjust something with corrected it. Perhaps you know of someone who has an idea about plumbing that could take a look for you?

You have a faulty ball cock. Since they are easy to change out and are quite inexpensive I would simply replace it. Click on back if you need instructions. Good luck, Tom

Or its possible that water level needs to be adjusted.

You have a faulty ball cock. Since they are easy to change out and are quite inexpensive I would simply replace it. click on back if you need instructions. Good luck, Tom

Looking at the pic - it actually looks like the part my mum bought to replace the old one - but the plumber adjsted it and it worked fine - so we did not use it in the end.

Thank you everybody. And thank you Speedball1, we bought and fitted a new ballcock and now have a fully functioning lav. Saved probably £50 on calling a plumber.
Very much appreciated, thanks :)