After work on Monday I headed to Pinocchio Sushi for dinner, afterwhich the CB400 completely died on me: the headlight came on for perhaps half a second and then there was nothing at all. The controller for the newly-fitted heated handgrips flashed at me as if to say they didn't have enough power, so I guess I should be thankful that Close Motorcycles hooked them up directly to the battery and not via the ignition as I requested.
Not thinking too clearly, I checked the fuses and ripped the battery out. Everything looked OK so I walked the bike down to the laneway next to the old Kingsford bowling club and hoofed it up the hill to Randwick. I think I read 12.7V — a little low but not dire — but because I didn't know how old it was I thought it'd be worth replacing in any case. Phil from Beaconsfield Motorcycle Supermarket priced a replacement at $160, ouch, so I got the 370 bus first thing Tuesday morning. He advised me that in addition to the fuses under the seat at the rear there is a main fuse which might have blown. He also suggested that the charging circuitry might be defective. All of that sounded plausible to me, though consulting with Dave about his recent alternator failure in Bonnie made me think that without one of those the bike wouldn't run for long.
Back in Kingsford I found the main fuse behind a side panel, and both it and the spare were intact. I swore frequently as I installed the new battery; hooking up the negative first is a beginner's mistake (I think) as I drew a fat spark just as I was finishing up with the positive. She fired up first go and there was no sign of short circuits or any other thing that may excuse the old battery. Fingers crossed I rode up to work and made it home after.
I was pretty happy with the little toolkit that Honda provides. I was less happy with how little room they leave for getting the battery into its cavity past the wires.