Chinese Dual SIM 9700 Insert SIM card problem

Hello,

I have Chinese 9700 Dual SIM. Since a week there was problem with SIM Card 1 Slot. It was just showing - Insert Sim Card and the card was unavailable. When I restarted the phone it was OK. But now the card is unavailable all the time. I have changed the SIM cards and the problem is definitely with the card slot and not with the SIM itself.

Any suggestions how to solve that issue without sending back to China?

I have also tried to restore factory settings, but to no avail, as I do not know the factory security code - I have tried with 0000, 1234 and 1111, but to no avail.

Thanks.