You can tighten it but I doubt that it will work. The O rings can be purchased from a NAPA or on line at
www.acsource.com. These o-rings shrink and break down over time. This next part your aren't going to like either. If you open the system to change the hoses you will also want to spend the extra $19 or $20 for a new receiver dryer and O rings that couple that to the barrier hoses. Then you will need to vac the system down and recharge it.