Run-in / damaged running surfaces in the housing or displacers are milled out in the damaged area. The machined area is then filled with a high-quality 3-component plastic (from aerospace technology). This is then milled flat and ground. This creates a seamless new surface on which the sealing strip can once again run with low wear and tear and, of course, can also seal properly again.
The cost of a repair depends on the extent of the damage. The repair can only be carried out in conjunction with a complete overhaul.