I changed the hydraulic jack oil in my sears 3 ton floor jack. I dumped the old oil into an oil container. Noticed a spring fell out of the drain hole, I reinstalled the spring through the drain hole, then filled with hydraulic jack oil and replaced the drain plug. I then turned the handle to the right (lock position) and pumped and pumped, no joy. I then removed the drain plug and turned the handle 1/2 turn to open and bleed the system. I pumped and pumped and with each stroke, some oil came out. I then refilled with oil and reinstalled the drain plug. I locked the handle in the lift position and pumped and pumped, no joy. what am I doing wrong?