Looks like RMS Express 1.5 is broken on Linux when following my previous posting.
I suspect it may be an issue with the .NET libraries, I’ll keep looking for a solution.
To revert back to 1.4.4:
Run “Uninstall Wine Programs” from your Wine folder on your menu.
Select RMS Express and Uninstall.
Unzip Winlink Express Install 1-4-4 and double click the installer.
Install with defaults.