1980 Vette Headlamps

Is there a way to manually lower the headlamps on a 1980 Vette? Mine are stuck in the raised position. I've had different issues with them over the years, but there has to be a way to lower them by hand. Can anyone help?

Thanks!  

there are a few articles on how they work and how to fix them..

http://www.vetteweb.com/tech/vemp_0212_corvette_vacuum_systems_guide/index.html

here is an article on an electric conversion..

http://www.vetteweb.com/tech/0408vet_c3_electric_headlights_conversion_kit/index.html