You may have a slug of air in the line which is feeding the B direction.
When you rotate to A movement, the B line is under partial vacumn, and the air does not affect movement.
When you rotate to B movement, the air is compressed and causes restricted responce.
In my hydraulic kit I carry a made up tranparent Tupperware container with 2 small hose barbs screwed into the bottom.
I fill this with fluid and connect by clear plastic hose to the ram bleed screws.
This way you can rotate the pump
continuously and watch for bubbles rising in to the container, at the same time non airiated fluid is inducted thru the other tube.
Proved a time saver when installing Octopus A/P ram sets.