Hey I opened a Veglia Tach on my mk3 to see if I could rebuild. Was told that they are not fixable but was able to adjust RPM settings by removing and reinstalling the needle with the position rotated with a little more preload against the stop. You can’t easily adjust the air gap between the spinning magnet and aluminum plate like with a Smiths Tach to calibrate. So don’t throw out your Veglia gages if they are reading way off. They might be salvagable. Pictures attached.