Hitachi FT-340 - what size insert screw?

[anytune]

Picked up a very nice Hitachi FT-340 tuner at a local thrift. Plays great, crisp and clear reception. I wanted to clean some dirt and dust from under the display glass, but have been unable to remove the insert screw securing the tuning knob. Very tiny hex head. Does anyone know what size tip I need? As this is unit is Japanese made (1978) could be metric. Any assistance appreciated.

 

[Punker X]

1.5, 2 or 2.5mm's are the usual suspects.

 

[anytune]

Thanks Mike. A 2mm was too large. That's the smallest hex-head I have. Perhaps Home Depot has a set of mini metric allens. Appreciate your help.