Some will say "change them"......
I personally don't subscribe to that idea as it isn't my money I'm spending, it's yours! After you go chasing and replacing it can soon mount up to £££'s and a year later you are back to square one!
A little trick that I have learned is to use:
A hyperdermic needle and syringe (easy to get hold of if a friend or relation has diabetis etc)
3-in-1 silicon lubricant spray (halfords stock it)
Spray a copius amount into a glass and suck it up with the syringe.
Inject into the outer edges at 12, 3, 6 and 9 o'clock positions until you feel slight back pressure on the plunger of the syringe. Spray the rest of the outer area with the silicon lubricant... Job done
Now make a cuppa, be proud and let it do it's work...
No more creak for around 9 months, then repeat as needed if it comes back.
The silicon will lubricate and feed the rubber bush and expand it just enough to tighten itself up against the alloy/ metal housing... Creaking only occurs when the bush gets dry and starts to harden and shrink.
Hope this helps