[Arran]

It looks like an American Bosch built Westinghouse, Westinghouse had their sets built by RCA in the early 1930s and had them built by Stromberg Carlson in the late 30s after Bosch went under. I think sometime in the 1940s American Westinghouse started building their own sets again. The Canadian Westinghouse sets were all built by Canadian Westinghouse, so while some models are similar to Canadian RCA and Canadian G.E Models, others are entirely different.
You should be able to glue the knobs back together if you have all the pieces. Wooden knobs often have a problem with chips and cracking and I think these may be more prone to it because there just isn't that much material since they are small, thin, and concentric. I wouldn't mind getting one of these sets, they look like they would be a decent performer.
Regards
Arran