Many thanks to everyone's input, I will try a "clean" build as recommended and hopefully post results back up here for future reference. Pound to fit, paint to match

.Duplex is a get;set; ... Try setting it. [PrinterSettings.Duplex Property (System.Drawing.Printing) | Microsoft Learn](https://learn.microsoft.com/en-us/dotnet/api/system.drawing.printing.printersettings.duplex?view=windowsdesktop-7.0) [Duplex Enum (System.Drawing.Printing) | Microsoft Learn](https://learn.microsoft.com/en-us/dotnet/api/system.drawing.printing.duplex?view=windowsdesktop-7.0) "Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I

Try renaming Form1 before changing the Startup in the project properties. OR------------------------------ I have also added a form under the form name I wanted (Like Title), again doing this before changing the Startup in the project properties, Save the project exit VS, open VS and load the project. When you go back to Project the drop-down should show the form you added. Select it, return to Solution Explorer and then delete Form1 properties or at least Exclude it from the project. Both of these have worked for me. ed