You are correct in saying both are on the same bulb, what you need to understand is that there are two filaments in that bulb. It is possible to have one blow without the other being affected. In addition, moving the bulb like you did can get the filament to touch and work temporarily. Please invest in a multimeter for your future troubleshooting growth. In addition, sometimes a visual inspection will not detect a failed filament. On a 2.00 bulb, I would do a simple swap to see if problem is resolved. Good luck.
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