"heard a lot of things rattling around so think it's time for a new camera..." -
Don't be so sure / give up on it so easily. This could save you a lot of money.
All my big cameras make rattling sounds when you shake them. There are bits and piece inside that need a surprising amount of clearance to function properly including the iris in the lens, parts of focal plane shutters, etc.
The real question is whether or not it works, and is it consistent. You can easily check the 1st by going outside on a nice sunny day. Put the sun at your back and shoot an average scene at ISO 100, f/16. If it tells you that the optimal shutter speed is around 1/100th of a second, produces a reasonably exposed image, it passed the 1st test. This is called the "Sunny-16" rule (Google it).
The next test is to simply take exactly the same shot 10 more times and compare the resulting images. If the exposure and focus don't vary by a noticeable amount, it means that wear and tear, as well as lubrication are all probably just fine.
If it fails one of these tests, let us know.
T