John,
The dimensions are approx, but close. Body dia 2mm, head dia 3.5mm, length 4mm, shoulder dia 3mm, shoulder length 1mm. I have attached a photo of the existing screw. Click for enlargement.
I took a screw from the acc. shoe of the Canon meter. It is the proper dia & thread pitch, but it is too long, no shoulder and the head is too tall.

Thanks,

Gerry