If it leaks its toast. If it isn't, can you do a bounce test on that corner at both max and min setting. Both should stop bouncing within 2 or 3 cycles. If you can feel the change in settings but both still control the bounce in those 2-3 cycles then the shock is still working properly. If you can't tell the difference between min and max setting, or the shock allows that corner to continue to bounce, then it's time to replace it. Again, ANY fluid leak means the shock has failed.