Damn! I too looked at these same machines off ebay when I first started my CNC research. It was on this very forum I was warned off it.

It seems like you have good technical knowledge and experience to understand its faults and shortcomings. God only knows the fix I'd have been in as a complete novice had I purchased it.

If you do have experience as it seems from your understanding, may I ask why you purchased such a machine?

I also fully agree with Dean in saying send it back for a refund. The seller hasn't got a leg to stand on. If these fundamentals are bollocks, there is bound to be a hundred other issues lurking even if you fix what you've already found.

And after you've sent it back, I can firmly recommend you speak with Dean. If you've paid the price on the ebay listing, you'll get a very different machine from Dean. Chalk and cheese. I have one and have been plain sailing from day 1 - apart from collecting and moving the beast into my workshop!