Here is some information that might be of interest. When I removed the rear main cap, the seal didn't look that bad, quite compressed but still in one piece. It actually didn't leak much. The new seal of course looked like a trapped piece of rope when installed in the cap. About a week later I removed the cap to adjust the bearing shims. The seal was really compressed and the surface looked very hard and shiny. A few hours later, still apart, the seal looked like a rope again. It shows I think that the new seal is quite resilient and that probably explains why a really old seal cannot perform as well.
