I have to call my instrument overhaul guy tomorrow to find out the correct sender for my oil psi indicator. I thought it was wrong so I cross checked it with a certified test gauge. It was over 20 psi low on the bottom end. If I have the P/N of his water temp indicator I will also ask about it. I had all the gauges in my 1976 TR6 overhauled including tach and speedo and it changed everything. Turned out that it had defective water temp sender installed
Sad to say but I have had some bad luck with today's Chineese electrical parts. An out of box failure of a new part when trouble shooting will drive you crazy because once replaced you should be able to eliminate that part from the process.
Vegletti Borletti has made good quality instrument for many different cars for a long time but after 40 plus years they can loose calibration. I'm way past 40 and totally out of calibration. I check for the P/N before calling my guy Morris.