I like the current sections myself, topic based, IE test equipment, repair etc.
MAYBE just adding a brand subsection under each of the categories, such as Repair/Fluke, or Repair/Datron etc.... that way the current main topics are left alone without mixing up the topics, and it adds refinement and easier browsing to items of interest.
For instance, when I have been working on the Datron series of equipment, I had to do multiple searches for each model in the series to try and capture as much info as possible, if they had all been in the same sub category it would have made that a lot easier, the same can probably be said for some other equipment which has a lot of similarities across the instruments made by one manufacturer.