That's the simplest explanation and easiest to check out, by looking for a broken filament in the bulb.ok - I think I understand - there are two filaments to each bulb and the right tail light filament is burnt out - thanks!!
Based on your first post I'd guess it's the right brake light filament but you've got the right idea. You might want to replace both bulbs while you're at it.there are two filaments to each bulb and the right tail light filament is burnt out -