I downloaded the latest version and ran the plusifier. When it asked me to open a file, I renamed my original Jazz2.exe to a backup name, and then renamed my old plus'd file, Jazz2+.exe, to Jazz2.exe. I selected the same for the save file and typed no when it asked if I wanted to make a backup. The plusifier seemed to work, but when I tried to run the program, I got something of an access violation. I apologise for not writing it down. It continued to do this until I re-ran the plusifier and now it seems to be fine.

Thought that should be known if nothing similar has been reported. I'm not sure if my renaming caused a simple error or something else did, but there you have it.