Really don't know how that drive belt fitted around all 3 pulleys on yours.. Lol. There ain't much movement in the mechanism to get my drive belt around the 3 pulleys.
Check where you have the idler arm bolted to the chassis. Maybe a photo showing the full system like mine does may help, because your arm (with the brake pad and idler pulley) seems to be coming in at a greater angle to the drive pulley than mine does (as shown in these two photos). It may just be the angle of our photos but, according to my train of thought, the brake pad should be tight against the drive pulley if the pedal is all the way back from the throttle position.
Mine is happy working in the same rod hole as you have shown above.
