Theservice kit for the Hill MK4 PCP pump includes a set of seals and a micron filter for self-replacement.
The most common symptoms of a sealing problem are resistance when lifting the pump lever and a tendency to bounce when pumping. The piston seal is a key component of the inflator, its life can be drastically reduced due to overheating and lack of lubrication. You can recognize the MK4 pump by its composite base.
