The solution provides an easy quick view of how the SIM connection circuit being mounted or assembled on Nokia C7 PCB board. In this solution you can easily trace teh SIM connector line paths and check the the corresponding components connected to it.
Nokia C7 insert SIM card solution with jumper ways
For further and deeper troubleshooting if the SIM flex board is okay, you may then proceed to check the particular components that holds or connected to sim card circuit. Check also each corresponding line paths, supply voltage and ground line connections.
If both all the line paths is working well and also already tried installing a new SIM flex board but the insert sim card problem still exist. Reworking the power IC (GAZOO) might solved and fix the nokia C7 insert sim card problem. Hope this solution may help.