2000 f-150 7700 series, haing a proble with 4x4, voltage on solonoids r fine, front axel engages, tires won't lock in, I pulled the vacume lines off the 4x4 actuator and the red line has vacume and blue line seems clogged? I reversed the lines on the actuator and wheels locked in, when blue line is disconnected frm solonoid And actuator I can blow air through it but when connected to solonoids blue line seems clogged, is it just my solonoids that's malfunctioning?