As a result of the problems encountered last time, I made a couple of improvements to the hardware.
Kettle Check Valve
I fitted to the input of the Kettle from the Mash Tun a one way check valve. This prevents the Kettle contents siphoning back into the Mash Tun.
Mash Tun Output Filter
I moved the filter from the input of the Fermenter to the output of the Mash Tun. This was needed to prevent the Mash pump clogging. I used the Fermenter filter because any crud was being filtered before reaching it.