
I dont have a machine with one of those but they must be a better single spring motor than the earlier types if you were getting two records from one wind.
I'd say one of the Victor springs will fit it, but you will probably have to remove the spring & measure it.
They're only a small spring so it shouldn't be any problem removing it from the barrel.
I've got a video on youtube that shows you how if you haven't done one before.
Depending on where the break is, you might be able to repair it, but even loosing 3 or 4 inches off a spring can make a huge difference to the power, especially if it's broken in the inner coils.
Another book you might want to get is called "Collecting Phonographs & Gramophones" by Christopher Proudfoot. It includes a section in the back that covers repairs & restorations etc. It also has a neat section on HMV machines that you wont find in any other books, as well as coving Edison, Columbia & many European/Continental machines.