add to the pump on my Potterton 11 boiler has stuck?

If your boiler is an old one, it doesn't have to be in the boiler casing...it will be in the central heating pipe runs though, should be accessible and often found in an airing cupboard or similar. I think a lot of Pottertons used Myson pumps. Try google for some images, to help you find what you are looking for?

John
October 2009