My 2009 accent manual transmission slips, but only after it is warmed up and when there is some weight in the car. Have bout 56000 kms on it, garage maintained which they said that everything is fine so I do not know what to do. They did say to show up when the symptoms appear but it is hard to do when it is random. Does anyone know what it can be? I just did 250km trip and no issue but on the way back it acted it up. Any ideas?