If its on the output of the pump, it should be pushing it away unless you meant by the input.
I would try tilling the case around to see if you can get these air pockets to the res.
mine XT had problems a while back, i stripped it down to find the placcy rod inside was the problem, purchased a new rod and all was well.
pain in the butt to sort it out, would i buy this product again, hell no more trouble than it is worth, D5s all the way