Brake light not working/Doesn't need replacement

Try moving the bulb around in the socket with the turn signal on to see if you can make contact with the bulb.

Even though the turn signal is working? Should I try to get someone to hold down the brake pedal while I'm trying that?

Yes

Just tried that and there is definitely a connection with the bulb. When I turned the head lights on, all of the tail lights worked, but still no driver side brake light. Would that indicate the brake light switch is bad?

That worked! Thank you so much! Can't believe it was that easy.

Great! Sometimes it is not easy with wiring. Glad it is working.

Sorry to exhaust the question, but I'm having a similar problem again. I can literally hit the tail and the brake light will start working again for a short while, but by the next trip it's out again. Obviously an electrical wiring issue, right? I don't know if I should order a new assembly or finally cave and take it to a mechanic in case the wiring problem goes deeper.

If you are able to tap the tail light lens to make it work, there is just a bad connection right there at the bulb. You may need to replace the bulb socket itself, not the hole lens.