Tefal 2931 steam switch problem?

Our 14yr old Tefal 2931 steam generator iron will not produce the steam from the hot plate. The safety pressure release valve blows off the steam, but the hand trigger wont allow any steam pressure to come from the hot plate. The iron heats up as normal with all the lights working as usual.

The iron has been slow recently producing steam

Please can you help I dont mind refitting a part from any advice given.

Thankyou