left and right bumpers/triggers

Mitchell, the first thing I would try to do, clean the triggers. After a few years, there might be a lot of grime and debris that accumulates on/in the trigger. You should get some isopropyl alcohol and a q-tips. Wet the q tip and clean the edges of the trigger well. Should this not work and you feel up to it, dismantle the GBA. A good video to direct you is here Check on the trigger springs and button, make sure they are all in working order. You can purchase inexpensive replacements here and the buttons right here, Hope this helps, good luck.