Super functionality, but weak power supply and receiving part

After we (had we 2 thereof) 823 with the Kathrein were very happy, we have the 922 gained for the HD era. the service was exactly what we wanted. All the best. Super features great programming ....
After 1.5 years the reception is poor, only 90% signal strength and 70% quality. The Humax, which stands next to it, indicates 100% / 100%.
After 3 years, the receiver turns out: The electrolytic capacitors in the power supply are out. We already knew from 823. So from the workshop.
After 2 weeks it runs again. Yesterday it fails on many channels: 60% signal strength, 30-40% quality. Regardless of the band or polarization. The Humax next to it shows 100% / 100% and has no problems.