You can't. You must replace the entire thing with another sealed beam. See sources and related links below to lookup sealed beam lamp numbers by vehicle make, model and year.
To change the headlight bulb in a 1978 Pontiac Trans Am with a sealed beam unit, first, open the hood and locate the headlight assembly. Remove the retaining ring or clips that hold the sealed beam unit in place, then carefully pull the old unit out. Insert the new sealed beam headlight, ensuring it is seated properly, and secure it with the retaining ring or clips. Finally, test the headlight to ensure it is functioning correctly before closing the hood.
If I'm not mistaken you should have sealed beam headlights as mine does. If you are getting water into a sealed beam headlight you will have to replace the lamp. The old one is no longer sealed.
Is it a plastic prong sealed together
A sealed beam headlight is just that. The unit is sealed and you replace the entire light. A composite is made of pieces that's why the name. To replace a composite you put a new blub in the back.
Yasa Bobaganoosh
bulb
sealed beam
I do not have the answer but I own one of these and it is still sealed.
sealed beam
A sealed beam headlight may smoke when switched on due to overheating, which can occur if there's a short circuit or if the bulb is drawing too much current. This overheating can cause the internal components of the sealed beam to break down, leading to the release of smoke. Additionally, if the glass lens is cracked or damaged, moisture can enter and cause internal failure. It's important to replace the sealed beam unit to prevent further electrical issues or fire hazards.
If it is a sealed battery you do not open it. If it is not a sealed battery simple remove the caps.
To test a 2 prong sealed beam light, first disconnect the light from the power source. Then, using a multimeter, set it to the continuity test mode. Touch one lead of the multimeter to one prong and the other lead to the second prong. If the multimeter beeps, it indicates that there is good continuity and the sealed beam light is functioning properly.