QTR-Quadtone RIP

I have a Brother MFC-240C that I use with Windows XP. The printer is 2 years old and has done a decent job in the past. Last week it stopped printing. The error message said that the ink cartridges were empty. However, when I removed them there was still plenty of ink, so I shook them up and replaced them. The printer still registered that I was out of ink. I had been using non-OEM ink cartridges so I replaced them with Brother ink cartridges. It still registers as empty. I think the first ink cartridges might have leaked when I reinserted them. Is there any way of cleaning the electronic devices that monitors ink usage?