Hi Karen
The creak is almost certainly the stabiliser - I know the problem well !
As Rob says, clean the ball and pads carefully. HOWEVER, I do this religiously before every tow but still get the groaning / squeaking starting after only a few miles. I use fine emery cloth and brake cleaner as recommended and have also used 3M Scotchbrite abrasive pad. Nothing seems to work for more than a few miles. I've even fitted a new Alko towball. Alko claim in the caravan handbook that the pads in the stabiliser should be good for (from memory) 30,000 miles. Mine has only done 7,000 and have never been grease contaminated although I was on the verge of greasing the ball, out of desparation, when touring in France.
I have emailed Alko about the problem but had no reply. Perhaps they may like to respond through this forum. Has anyone else any suggestions ?
John M