no you right rubyrubyroo
they are fantastic machines and i dont mean to give them bad rep.
is confordant enough to pull it to bits and check the connection then it could be a very easy fix should it be a loose connection, however if like you say its a bad joint a re-flow might work but its only a sort term fix however and im my opinion a waste of money
I cant say 100% that im correcting the mobo failing, however after spending several days on one alone to diagnose the problem and not coming up trumps with specific hardware and again with several more with the same problems i am betting that it is a failing motherboard once again
I would however like for someone to come along a prove my diagnostic wrong because despite their faults they are cracking machines and hate seeing them go for scrap