hi guys as youve all had more experience than me at this could you tell me the easy way (if there is one )of replacing the rubber diaphram in the diverter valve on a vaillant vuwgb282e combi boiler , i did replace this 2 years ago as its on my friends boiler and it was a right pain ,i had to remove the complete valve from the boiler but was just wondering if i had to do this