yong heng and filter

Make sure that the leak is at where you think it is. If it is from the female brass fitting on the end of the hose, check that there are two O-rings there. If not, that may be your problem. If the fittings won't couple or the locking ring won't close all the way, replace either side until you have a safe union. Usually, if they fit together OK they will seal if the O-ring or rings aren't missing or damaged.