Default SIM Card not found randomly

Hey guys,

For the past few months I get a problem with the card "loosing the simcard" suddenly, I can't reproduce it, I think it might be some contact in the phone as it happens mostly when I walk with the phone in my pocket. The phone suddenly searches for a network, doesn't find - and then SIM card missing. I triede this with different sims and no go

I opened it up, tried to press things together and also put some contact cleaner...

Does anyone have experience with such a problem? can point me where to check on the PCB?

--Summoner
--------
SE T68->Casio E200->SE P800-> iPAQ 3970 -> SE T630
HTC JasJar -> Incredible, but needs a new M/B
HTC Artemis -> Cute and Furry!
HTC Polaris -> Didn't connect to...
Samsung Omnia -> Nimble little phone
HTC G1 -> Linux in my hands...
Omnia B7610 -> Power in my hands...
Beam -> I can see the light!
HTC HD2 -> Big and Bad
Atrix4G -> NVIDIA in my pocket (!)
Evo3D -> Opened my eyes 8)
HTC One -> Full HD [WoW]