Help troubleshooting Soundcraft Series Two

Hi all,
i recently purchased a used Soundcraft Series Two console and everything else is working as should but channel 5 seems to be partly dead.
I can get signal to the channel via the return of the insert point, but no luck with Mic and Line inputs. Direct outputs and aux sends on that channel work also. So its just the mic/line inputs.

-Markus

Feed a signal into the defective pre and check if you can get a signal at the direct out (switched to pre) or at the insert send. (EQ off) Often the insert jack socket has trouble with it´s switchcontacts. In case the signal is present then replace the insert jack or use a TRS jack with tip bridged to ring. This shortens the switch of the insert socket.
If that doesn´t work then good luck. Your desk is a single PCB design, which means removing all caps and losening all pots to get access to the component side of the PCB.