I have a Hobart modle LXih that leaks from near the top on right rear There is a unit that has a small hose and two larger ones

Sounds like you're referring to the vacuum breaker. It's very easy and cheap to rebuild, if it'll come apart - sometimes they're very difficult to unscrew the top and the whole vacuum breaker must be replaced.

Obtain a rebuild kit for the vacuum breaker from Hobart (about $5). Remove the screw from the top of the vacuum breaker and take off the chrome cap. Use a cresent wrench or channel lock pliers to remove the now accessible upper section of the vacuum breaker. Clean all scale from the brass piece you removed, particularly from the center pin and the surface at the bottom of the removed brass piece, where the threads start. This surface is the surface where the moving float's rubber seal will come up to and form a watertight seal. If you're unsure what surface I'm referring to, place the white plastic float onto the removed brass piece and take note of there the orange seal of the float contacts the brass - this is what must be clean, straight and flat to make a good seal with the new float. The center pin must be clean so that the float easily moves up and down on the pin without binding. Also clean all scale from inside the body of the vacuum breaker, although not as critical as long as the float will move freely inside the body of the vacuum breaker. Once it is cleaned, reassemble and you're done.

P.S. it's possible you may be able to stop the leak simply by disassembling and cleaning the scale as described above, but considering the cost of the rebuild kit, you should replace the float from the rebuild kit as the float's seal shrinks over time, which may in fact be your problem instead of scale deposits, or both.