You need to ask the owner if the light is red or if it is amber. With the service run switch in the service position the hydraulics will not work unless someone has done some modifications they should not have. The problem could be a seat switch, seat belt switch, seat harness or even the instrument panel. Don't operate this machine if the safety equipment has been by-passed. You can probably replace all the components of the safety circuit, except for the instrument panel, for about 200.00. The instrument panel has lines around the various windows. If the lines or silver in color you may have a bad instrument panel. If the lines are gold in color the problem is likely somewhere else.
As for the backhoe, you may need to make an upper bracket to mount to the front of the loader where you enter it. There are two hooks already welded to the lower front.
Make a lower offer.