The oil absorber in the PTR compressor and the rotary valve for Helium flow are supposed to be exchanged every 15000 hours running as a part of the PTR maintenance. Replacement units were ordered. The oil absorber was replaced, but the rotary valve was the wrong model. The correct rotary valve model arrived in the beginning of November, but turned out not to work properly. A second rotary valve came, but this one failed as well. We are still waiting for a functioning unit. The old unit is still running as a clock after nearly 30000 hours running.