My Stack rev Counter and speedo have just stopped working this evening while driving the car home . The car had been sitting in the sun all day and was hot - I drove about a mile and the the speedo stuck at 26MPH and the rev counter at 2400RPM. After about an hours driving the rev counter began to respond, but now had recalibrated itself so 1000RPM was showing as around 5000 RPM. It then became intermittent and now 1000RPM shows as zero, and speedo is stil stuck at 26MPH. There is some condensation inside the perspex screen - I guess the hot weather has vaporised some moisture inside the gauges. Power supply to the instruments is OK as odometer, temp and fuel gauges still working OK.
Any suggestions as to how to fix this?