the brake cable CAN'T slide thru that type of yoke, under load.... the gray tube prevents it from doing so.
replace that bad cable NOW, Please... or we might be discussing crash repairs next.

check spring engagement with the boss on the fork (most have three holes to hook into... if the springs are good, then the brakes SHOULD retract evenly)
and set the brake pad posts to where the brake arms are about vertical when the brakes are engaged.

one thing i see frequently is a stuck bushing in one of the arms... some use a floating center bushing of brass.. if it sticks, then that brake will work only if the bolt is left loose....

i've seen a mashed washer cause drag on brake arms too... the washer contacts the arm, creating drag...
people get ham-fisted when tightening the allen bolt.. this can mushroom the end of the post, causing drag... you'll be able to feel the flared post end, if so.. or a check with a small file can show it too.

Do NOT apply thick grease to the posts.. it WILL CAUSE drag... it might help temporarily, but always gums things up in the long run,by attracting and holding dirt.
A light smear of light weight grease is ok, and might inhibit rust, if the bike needs to sit in the rain at times.