Hi @Mugsy's RapSheet,
Welcome to Microsoft Q&A!
Is it targeting .NET Framework or .NET? Have you tried to repair your VS2022?
To open Toolbox, you can choose View > Toolbox from the menu bar, or press Ctrl+Alt+X.
If the Windows Forms Designer fails to load, you can try to clean and rebuild the project or solution.
If it persists, please share us detailed error message to investigate it further.
Sincerely,
Anna
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