Hi Yow;
1) Can you try GS v9.18 as I believe that they just updated the fonts in the latest version to improve PDF rendering?
2) Can you also try commenting out the following (alternative to #1 if it does not help) ...
// dw_1.Object.DataWindow.Printer = 'Sybase DataWindow PS'
// dw_1.Object.DataWindow.Export.PDF.Distill.CustomPostScript="Yes"
Regards ... Chris