Sony Drum Gauge, pn J-6250-800-A

Sony Drum Eccentricity Gauge II. Used, in original packing, VVG condition.
£176.29

This is a head drum gauge for measuring the eccentricity of the head drum.   It is a precision watch style gauge built by Citizen Watch Company.  The gauge bears 2 part numbers:  J-625-080-0A on the box, and JB-5080 on the gauge itself.  

The instructions indicate that these gauges were designed to be used on Sony One Inch Type C machines, such as the BVH-500, 1000, 1000A, 1100, 1100A, 1180 and the BVH-2000, 2180, 2500, 2700, 2800, 2830. 

If you are involved in maintaining Sony 1" machines, replacing the heads is impossible without one of these gauges.