1929 Model A - Headlamp issues

[Ace1347]

Good afternoon, I am now the proud new owner of a 1929 Model A Roadster.
I am reaching out for input in respect to the headlamps. The car has been converted to 12 volts and when I brought the car home the headlamps were fine. I noticed they go dark at a stop and once the idle picks up they grow bright. I plan to take a look Saturday morning but am looking for input if possible. A longtime lurker to this site and excited to interact more often.

Thank you in advance!