Hi PD's.....not to be baulked with this and after ZERO response from Miniature Gauges UK

.........I have discovered
1. the lower tapping in the rear of these miniature brass cased gauges is in fact a 10 BA jacking screw tapping
2. by screwing a 10 BA brass screw impinges or contacts the inner face of the gauge dial
3. by continued rotation of the 10 BA screw the case bezel is displaced however it may have caused further damage to the burden tube hair spring

4. it also pops the needle pointer off the spindle

To cut a long storey short......I have stripped two gauges, marked the
RED line & reassembled them.......
5. now to see if they still work.......

......Derek