Who has an explanation for this:
Noticed the voltage shown on dash gauge was low after starting and warm-up (hand brake on as well as ‘brake’ light) - checked battery with voltmeter and measured only 11.7 volts. Ran engine 10 minutes and volts remained low. Charging warning light was not on - but figured it might be burnt out due to age. Went to NAPA picked up a new alternator. Was moving car to install and released hand brake (brake light goes off) and voltage on gauge went up - checked again at battery and it read 14 volts. Set hand brake again (brake light goes on) but reading remained at 14 volts. Turned engine off reset hand brake, turned over engine - again 11.7 volts. Released hand brake back up to 14 volts it goes again.
Took belt off alternator, set hand brake, started engine, no charge warning light came on, volt reading on gauge low. Tried to release hand brake - it felt like it was out of adjustment/loose and brake light would dim but not go off - all the while volt reading stayed low.
Put alternator belt back on and started engine - rig resumed working as it had been and hand brake (and light) again worked properly