Driving any vehicle without brakes is like having a an Evil Knievel type death wish. The lift weighs more than most vehicles on the road but only has two wheel brakes brake. Lifts don't go as fast a cars but they can build up a lot of momentum to stop and shorten the life of an already well worn vehicle. What is the back-up plan to stop the unit if an over stressed axle 1/2 shaft, differential or trans shaft/gears comes unglued? Throwing out a sea anchor won't work. Best to tag it out of service until fully functional and operational. Or buy a good used one from a reputable dealer. - you'll be better off (economically & safety wise) in the long run.
With scrap prices today you can get enough money for a partial payment.