Dont use teflon tape. What you want is Loxeal Thread Sealant. We use it regularly to reseal pipes and fittings in machines whee the mating surfaces are damaged or pitted enough not to seal by themselves. You just need to take a look at each joint to see where the seal occurs and make sure you smear the sealant there without getting any inside the pipe or fitting. You should be able to get it at Reece or any plumbing supplier.