Updated the SA-5 page with more information

Received some welcome new information form Gavanti (OSG Forum) which I have now added. We now need someone with an SA-5 to open up the pickup to see what’s inside….  to confirm my theory about the pickup differences as observed by Gavanti.

On the left SA-5 headstock………  on the right SA-50 headstock.SA-5 Yamaha Logo - wider and shorter letters SA50 Yamaha Logo - Compressed in width and taller letters