The 8000 doesn't HAVE and embroidery unit. It's built in. I have the 9000 which is the model right after it. The embroidery section is on the main menu and you attach the hoop directly to the machine. You will likely find that it will be at least a $200 repair, maybe more if there are circuit boards needing replacing. They'r e great machines but you'll have to decide how much $ to put into it.
Most dealers would likely give you a free estimate, however I'm sure they're going to try to persuade you to buy a new machine. I still have my 9000 and don't plan on parting with it until it poops out. It rather sounds like yours may be too far gone to be worth the costs. You could search ebay(closed auctions) to see what used 8000 machines have sold for and sort of get an idea what the "worth " of the machine is and go from there? If a used 8000 is going for much less than it would cost to repair...you kind of have your answer.