just rebuilt my engine for my rst and found that the oil pressure sender unit for my stack gauge has broken, ive tried a couple of other sender units but they both send the needle on the gauge the opposite way, ive found that demon theives sell the sender unit for the stack gauges at £70! i can buy a whole new gauge for only a couple of quid more than that, does anyone know what else i could use? just dont like not knowing the oil pressure.