Good old YouTube! How on earth did we cope without it. I have found a lady in Australia of all places - you would really thing of Australia and knitting wouldn't you? - and a lady in New Zealand - who are real whizzes and they have videos of how to do maintenance and repairs.
This is the icky mess the the sponge bar was - it is supposed to be a thick foam pad strip - I cleaned it and used insulating foam tape to replace it - much better.