Sending it out to repair is certainly possible but it is not cheap as most hydraulic repair shops will charge at least $100-120 on the low side. Consider yourself lucky it lasted 33 years. I have seen "newer" Lincoln 93642 with broken u-cups that lasted maybe 15 to 18 years. But the problem seem to be one were if the jack is used only occasionally, then the u-cup has time to harden and will eventually break up sooner than a jack that is used regularly, as the use seems to keep the u-cup material pliable for a longer time. Still, it will eventually come the day were the u-cup will become worn and/or brittle. At this point, the jack becomes dangerous as a brittle u-cup could break suddenly and drop the car in an instant. And even if you use jack stands, it still can be dangerous as it could drop the moment you are setting the stands under the car or removing them.
So, my recommendation to anyone using a jack with more than 20 years of age, and that has been used on a regular fashion, to replace the seals,
just for safety reasons, if nothing else. No one uses their tires for 20 or 30 years nor their brake pads because these wear out. And so do the piston seals and the u-cups, as these are compressed against the cylinder wall when under load and they move out in the cylinder in a compressed state, so to prevent high friction and premature wear, the cylinders have to be well polished instead of having the cross hatching car engine cylinders have. This would wear the seals pretty fast if the jack is used every day, like in tire shop.
Check the links below for an animation of how an u-cup compresses against the cylinder.
http://systemseals.com/fea-animations/R01 Urethane Rod Seal.gif
http://systemseals.com/fea-animations/P27 Urethane Piston Seal.gif
If the jack is used a few times a year, or goes unused for some years because you have more than one jack, for example, consider replacing the seals after 10 to 12 years, even if you think these are in good shape, and save yourself some future grief. It is not too expensive if you can do it yourself. This applies to jacks using
urethane u-cups or any other type of main seal made of urethane. Just consider that seals manufacturers have different "shelf life" for urethane u-cups; some state the shelf life as 5 years, others set it at 10 years. This does not necessarily defines or limits the working life of the seals but it gives you an idea that these seals do not last forever.
After all, these seals were meant to be changed at some point in time, just like the seals in any other type of hydraulic equipment but most jack owners want, and expect, the seals to last forever, so when the jack bleeds off, after many years of use, they are baffled as to what can be causing this. And the jack does not has to show an external leak to bleed down as the leak is internal. But yet, many people think that if the main ram seal is broken, or worn out, there must be an external leak, and if there isn't, then they think it is something else and not the main seal.
