This Parker fly is a real beauty. A problem with it however, was that the nut slot for the G string was a bit tight. This resulted in an accurate tuning stability when using the tremolo system, and when returning to pitch after use, the string would be sharp, leaving an undesirable sound. 
In order to remedy this, I widened the slot slightly so that the string could pass freely after lubrication. I then attended all of the other slots in the same way as well, and then the guitar began to behave in the intended way. 

This is a stunning instrument and a really interesting axe to work on!