foto of switch of lights on handlebars international

According to the Lucas catalogue I think these may be the correct ones. I went through this for my 1938 ES2 a couple of years ago and found original boxed ones!

Following on from Colin's post attached is a Lucas switches catalogue.

A full Lucas catalogue is too large a file to attach.

Useful Lucas catalogues can be downloaded from the Bright Spark Magnetos website:

http://www.brightsparkmagnetos.com/library/Parts%20lists/index.htm

Here is a scan from the Lucas catalogue showing the original specification for your bike. 

This manual has the clearest wiring diagram I have that applied to all mid to late 30's Nortons apart from the panel tank models. 

There were changes between 1935 and 1939. In terms of wiring, this included the introduction of Compensated Voltage Control to replace the earlier Third Brush and resistor system. Obviously, the wiring changed accordingly.

The brochures seem to show a dip switch which was screwed directly to the bars via a steel cover rather than the clamp-on type (which were what Lucas supplied with their universal after-market lighting sets).

Are you using 7/8" or 1" handlebars ?

The Lucas catalogue shows several variants of the type 9 dip switch. The wrap around band, as I have, or a half band that screws to the handlebars. Careful study also gives variants for 7/8 and 1 inch.

There is also a difference in the shape of the dip switch handle. The rounded shape for pre war and a diamond shape for post war. 

I thought the 3rd brush systems were pretty much redundant for the 1937 season. 

…System confirmed on my 36 CS1.  Switch in tank panel with open wound resistor!!

Jon