At this point I'd recommend trying the drive in another computer. If you have the same problem then the drive is probably toast. If it works then backup everything asap. If it works, then either the port or something on the MOBO has given out. As far as replacing the controller. It's an almost mythical thing. I've heard some people have done it but also heard that some drives a lot harder to work on than others. You'd really have to do some more research, I recommend going to forums for manufacturer for that. At five years, its likely the drive has run its course. I've had some make it 10, but most usually go in the 5-8 mark.