what dia are your hubs?
most of these ebay machines arn't worth the money. if your very handy and can rebuild one, like new controllers and software they might be ok but if your gonna put in a couple grand to rebuild it why not just get a decent one from the start.
If you look at machines from US based companies selling re branded lasers from china and see that the prices are 2 to 3 times as much as the one your looking at plus they want shipping. this is because they are way better then what you'll get on ebay. so if your paying 2 to 3 k for a laser its a piece of junk.
Look at Rabbit LASER USA, Boss Laser, Thunder Laser.Yes there more money but a much better machine and you will get US support which you won't get off ebay.