I am a complete noob about adjusting a front 3 speed derailleur. I am having trouble getting the barrel adjuster for the front derailleur to either tighten or loosen the cable. I am wondering if the barrel adjuster threads are stripped and perhaps I need a new shifter. The shifter in question is a Shimano st-ef50-L


Currently the cable tension when the chain is on the smallest chainring is just tight enough that the cable doesn't sag or flop around. When the chain is shifted to the largest chainring the cable is tighter. Also, when the chain is on the small chainring the cable moves in and out from the barrel adjuster about 1/8th of an inch but it tightens up when shifted to a larger chainring. Here is a video showing what I mean (please excuse the heavy breathing lol):




Do you have any suggestions? Does the shifter need to be replaced?