Default [Q] SIM not recognised

OK, I asked in the Xperia Z_Ultra forum and there were no answers forthcoming so I'll try here.

I brought a second hand Z_Ultra that was listed as "SIM not recognised" and I thought that it may have just been a kernel/baseband issue as we see lots of this in the ZU and Z1 forum. When I got the phone the IMEI was present and correct so it's not that issue.

This phone is a grey import so no warranty here, so that leaves opening it up...

Do you think it is worth the risk of opening it up, as the phone will no longer be water proof?
Do I buy a SIM reader and replace it, if I can find one?
Or do I just give it to SWMBO as a wifi tablet and cut my losses?
Alcatel One Touch "easy" -> Nokia 1110i -> Alcatel ame-408 -> Motorola Razr v3 -> Huawei u8100 -> Sony Xperia Z-Ultra

ROM:- Carbon
Kernel:- Pimped Kernel

Thankyou to all those that have donated to me over 2014.