I need help with under the dash wiring brake switch and such

Do as suggested, check your connections, I like dielectric grease too. The one that is not coming on, could be ground, the new bulbs are not what they used to be. Had basically the same problem as you are having, for the hell of it, I took the new bulbs out and put 2 old used ones that I had and guess what, they worked. So it may be simple or it can be difficult.