Got a problem with the charging system on my 1984 245. When I turn the key on, all the indicator lights EXCEPT the battery light come on. I know this means the charging system won't work.

First, I took the instrument panel out and confirmed the bulb isn't burned out. It lit up fine with direct power.

Confirmed that I have constant power into the alternator at terminal B+. I've got power coming out of terminal 61 (the one at the bottom of the alternator, that drives the instrument lights). The ground, out of terminal D+, is also good.

Three years ago, I had a problem with the battery light and it turned out to be a bad connection at terminal 61; once I fixed that, the system has worked perfectly since. I checked that closely today, and there's no problem. And besides, the other instrument lights are getting power. Also, I replaced the voltage regulator a couple of years ago, so I doubt it would be that going bad.

FWIW, when I got home and turned the key off last night, the battery light came on like it's supposed to --- but it only remained illuminated for the briefest instant, not the full second or so that it's supposed to stay on after the key's been turned off. That's what made me suspect something was up, so I turned the key back on. Sure enough, no battery light.

What else should I do to troubleshoot this thing?