I just scored an imagewriter II from the local thrift store. It came with a whole bunch of cables and in the box, so I don't think it's broken.
I just can't get it to work. When I try to print something, I get an error message that says that I need to press the "select" button, which I did, but still got the same error message. I have driver software, so I don't think that's the problem either. I am running it on a 7100.
Try the self-test to see if it's working. Hold down the foem feed button while you power up the imagewriter. When the print head centers, release the Form feed button and it should print out a test page.