Worcester 24cdi no hot water - is DIY job safe?

Hi after reading some articles on here about no hot water through my worcester 24cdi boiler and reading worcesters fault finding info on their website i located what i think the problem is, i.e. that the plunger on the water diverter valve, though extending to some degree when the hot water tap is open it isnt going far enough to press the microswitch to activate the burners. I have simply stuck on some additional depth to the plunger, that now presses the microswith and the boiler fires up as normal.

My question is though my water works fine now should I be replacing the valve anyway as the fact that it no longer depressed the switch is a sign that it is knackerd. Any feedback would be appreciated.

Thanks