If your shocks feel as though they have lost all damping control and are rebounding harshly (basically feels as though your riding on a pogo stick), more than likely there is damage to the internals of the dampers.
How you can determine if the shocks have internal damping damage, is you can remove the shocks and shake them to listen for a rattling noise. If your shocks are making a rattling noise, or if you have noticed a degradation in ride quality, this is more than likely due to the base valves being "blown out".
Generally, what we see cause this problem, is having too much sag set on our coil/air shock products, or the shocks being ridden in the deflated position for our air ride products. What happens is if the shocks sag too far, or the springs are set too soft, is there isn't enough preload in the springs to keep the shocks from bottoming out. Because there isn't enough preload, the shocks when bottomed out enough, will eventually cause the shock shaft to contact the base valve in the compression tube causing it to break. This results in the loss of all damping qualities.
To prevent this issue from occurring with your shocks, you will want to ensure your sag is set correctly. Please check out our articles in the How-To section, regarding proper sag adjustment procedures.
If you are experiencing this issue with your shocks, please please view the article on How to Submit a Warranty.