Recently the left shift, left option and less frequently the left command key on my Macbook Pro (2012; A1286) have been cutting in and out. One second they will work fine and the next they won't. Strangely, it seems the left shift and left option key either both work at the same time or not work at the same time. I brought it into the apple store and they replaced the shift key for me but it did not help. They said replacing the entire keyboard ($240) would be the only option for fixing it. I've tried resetting the PRAM and SMC and have dusted the keyboard with canned air. Can anyone please offer any other suggestions? Thanks!