Try this, remove the knob,put a piece of paper or foil in the hole at the back and refit. Sometimes the hole in the back wears making the knob slide to far down the shaft causing it to hit the hob before turning the valve on.
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets