When I search the help system, I never get any response
I would download the demo of TinkerTool System and run the “Repair Help Viewer” routine.

http://www.bresink.com/osx/TinkerToolSys4.html

Menu ▹ User – then the Repair panel – then Repair “Help Viewer”

See the online documentation:

http://www.bresink.com/osx/300644207/Docs-en/pgs/0220-User.html

Search for the literal text:

Repair “Help Viewer”

-ccs