DV... here's a tool that won't mess up the rubber seal.
Some all-thread (1/2" if I remember correctly) and a couple of couplers. I cut off about 1/4" of all thread and used some blue loctite to anchor the 1/4" pieces into the couplers. Then another length of all thread to connect the two couplers.
The just put the toll between the upper and lower ball joints with the nut on the lower ball joints backed off to nearly flush with the top of the threaded portion of the ball joint.. Crank on the couplers on the "tool" to cause the tool to increase in length. A LOT less, um, noise than the hammer method
