Vinegar is good for cleaning limescale from kettles. Leave it to soak overnight. Also if you happen to know a frindly farmer I've often heard my dad say that the product they use for cleaning milking machines works wonders for cleaning out kettles.
Angela Browne
October 2005
If you live in a hard water area the element may have scaled up, you can try a descaler to clean the element, or replace the element when you have done either of these you can buy a little wire thing to put in or use a small round stone about the size of a wallnut which will work just as well to collect the scale instead making your element last longer.
Put in less water. Ie only as much as you need as long as it covers the element.
Eric
September 2005
I can answer this question...
How do I make my Russell Hobbs millennium kettle boil faster?