Felt Seals are available via Olsen's Gaskets online.
McMaster Carr offers Low-Friction Oil- and Water-Resistant Packing Seals. Since they require lighter packing pressure than standard oil- and water-resistant packing seals, these seals cause less friction and reduce shaft wear. They are for use in pumps and valves. Cut them to size with a knife; then pack them into place.
Aramid fiber seals resist wear and abrasion better than acrylic fiber seals, so they last longer.