fuse blow, battery light

[A. P. Marki]

hi,

looking for some wisdom. A few weeks ago the #12 fuse (15 amp) on my 1987
4ks (120k miles) blew; fusebox indicates the ckt is instrument cluster,
backup lights, blinkers. I replaced it and drove hundreds of miles home
without incident. It has since blown twice: I notice the battery warning
light is lit just as the instrument cluster dials go dead, and it has
happened only just as I start the car.

Does this sound like an alternator or voltage regulator about to fail
completely? Can these show an intermittent fault like this? And why only on
startup? Or does it sound like an intermittent short somewhere?

Also, is the best strategy: bench test the alternator; or just get a rebuilt
unit proactively. The car will be seeing some heavy duty x-country mileage
very soon. (Other prep has kept me from pursuing this gremlin.)

TIA,
Andrew Marki