I have a close-coupled toilet/cistern and when its flushed, on refilling the cistern, there is a rumbling sound,(airlock sound). When I turn on the cold water bath tap in a quick blast this stops the rumble. The cold tap in the wash hand basin doesn't help nor does leaving the cold bath tap running?

This started when I redecorated the bathroom and had new flooring laid. The old flooring was sticky tile wood effect planks that were fitted under the toilet pan. I removed these by unscrewing the pan from the floor and had a bit of wiggling around to get the stuck flooring out. We noticed that there was a leak (don't know if it was there before or not, although I did always seem to think the floor was never dry!) behind the toilet, and further investigation noticed that on flushing that the water was coming out at the wing nuts below the cistern. These were loose so I tightened them, this has resolved the leak.

The noise isn't as bad if the toilet is flushed whilst you are sitting on it (don't ask how this was discovered! )

The only other thing to mention is that the toilet is now securely fastened to the floor and my lovely new flooring has been laid and sealed all around it, so I really really can't move it?

Also the bathroom is upstairs so I don't want to break something completely and cause a flood through to the downstairs!!

Any advice welcome,
p.s. I am a complete novice at anything diy especially, plumbing.

Which ballcock is yours?