Spa gauge stopped working.

I have got a spa gauge that reads oil pressure and coolant temp. It sometimes drops out showing negative oil pressures and was told by the previous owner that it might be a dodgy contact where the sender is contected on a sandwhich plate with the filter, so when i did my oil change recently i pushed it around a bit in the event i might get lucky and make a better contact. I dont think it made much difference but a couple of days later the gauge went completely dead with no readings or any sign of power. There is a small leak in my windscreen that lets a bit of water near my pods when it rains hard and it had been around that time.

What has caused the failure and how can it be remedied? Is there a fuse somewhere for these gauges that has gone for either of the above reasons?