The light pulse bright? I diod in the voltage regulator is going bad.
Disconnect the negative terminal of the battery
Remove the voltage regulator and clean ( to shinny metal ) all terminals ( including those in the harness that can be removed ) and especially the grounds
Reinstall it and see if it solves the problem
That has worked well for Jason and myself in the past -- all better !!
The grounds getting intermittent on these ---very old cars is very offen the cause of a high majority of the electrical issues They have
To me a sign of how very well these cars were engineered back in the day ( love saying that ) to still be performing at the high level they still are today