Left speaker and subwoofer both had issues, so I decided to replace all three soeakers.
Easy. iFixit’s guide ensured no trouble!
I also replaced the battery, so no my old Pro, which was donated to me in poor condition, runs beautifully and has enough sound too!
Pop an SSD in while you’re at it.
Getting at the left speaker with the mic cable was tedious, but overall, just be extremely careful of all the different connector types on the motherboard.