S13 Driver Window Rolls Up But Only Sometimes Down. Searched, Tryed Amp&Switch. Help!

[LJBS13]

i have a 92 240sx. i've been having an issue with my drivers side power window. the window will roll up just fine, but it will not roll back down. i have pushed the windows up and down switch buttons back and forth playing with it and every so often it would work just for 1 time to roll the window down. now the window is just stuck fully up.

I plugged in a working switch and a working amp and both did nothing. now when i press the up button i can hear the amp click, when i press down nothing. i also tested power to the motor, when i hit the switch up i'm getting power, when i hit the switch down the wires show no power, i tested both wires going to the motor. i cant find a straight answer on exactly how to further troubleshoot my problem i'm assuming i need to supply power directly to the motor to check if it is working still, if so can anyone chime in on the correct wires to tap in to or the proper procedure? Is the any other connections i can check? any info is appreciated