Cistern loud vibration on fill advice

[xpeterpx]

How do I best explain? When I flush the downstairs toilet I get a loud groan/vibration until the fill stops. If I turn the tap on next to it it goes away.

Seems like the fault is in the cistern somewhere but can anyone help with what might be at fault and how difficult it would be to DIY change.
If it helps its the ballcock style of internals.

Thanks for any advice

 

[Newboy]

Change the diaphragm washer in the ball valve