front brakes pulling to the left

I got an odd problem on 92 kenworth w900. When I step on the brakes it pulls to the left. Does it worse when the truck is loaded. I just put new shoes and drums on the front. It pulled before new shoes and drums and still pulls. S cams looked good. I thought maybee I had a broken slack adjuter but when you apply the brakes it looks like everything works and moves like it should. Has anyone ever seen one line get partially plugged on one side and cause an imbalance? This is puzzling...

front brakes pulling to the left

front brakes pulling to the left