Original post by: arbaman ,
There is most probably something faulty or oxydized, but A1342 are no easy machines to deal with. Loudspeakers and keyboard are inside a kind of tray that is glued to palmrest..maybe a little liquid was spilled in the past. An inspection would need plenty of work just to find out what's wrong. Maybe finding a used palmrest would be the easiest solution, providing the logic board is in perfect shape.