As a replacement for my much used 9200T a grade A 9150 should arrive on Monday. I know little about this model but just wanted a cheap replacement for the 9200T. I just hope it does as well as the 9200T.
Did you try a manual tune? Were there any channels in the 800s? Have you checked the cabling for damage or water ingress? It is unusual for the tuner to lose signal strength; usually they either work or fail. I agree that if the tuner is damaged then a repair wouldn't be economic.It stopped getting a signal on 3 of the muxes. We get a strong signal from Craigkelly and the other Freeview bits of hardware in the house are fine (same aerial). Then the signal on the remaining muxes started to drop off. So thought it time to change.
Have you tried the 9200 with the new aerial/cabling?