was the gen not a 7750? or was it one of the models which used a seiko?
According to the Tag website:
Calibre 1887
TAG Heuer Calibre 1887 . Swiss Made. Automatic calibre. Diameter: 29.3 mm (13''') — 39 rubies. Rapid date correction.
Movement performance
Balance frequency: 28.800 vibrations per hour (4 Hz). Power reserve: about 50 hours, about 40 hours when the chronograph is engaging.
Movement display
Hours — minutes — small seconds at 9. Chronograph minutes at 12 and chronograph hours at 6. Date at 6.
Movement decoration
Oscillating mass: 'Côtes de Genève' engraved 'TAG Heuer — Calibre 1887 Swiss Made'.