Thanks for the replies. Not cross threaded but must be old fabric washer so will replace. Thanks also for tip about doughnut washer, I will change this also. :)
Please help. I have just tried to fit a new syphon to the loo which was going fine till I tried to reattach the water inlet pipe to the plastic inlet. I can't get it to stop leaking from the joint. I have used the same fabric washer as before. The inlet pipe has an isolater so dont want to...