Master System Controller Port Problem

[77fordtruckman]

my master system refuses to let you push left, I have re-soldered both ports, all the resistors around them and the part where they go through the other side of the board, all the connections look great. I've tried 3 different controllers and they all did the same thing, they are all genesis controllers but I don't think that's the problem because they are supposed to be compatible. Any ideas what else could be causing this? a bad resistor maybe?