[RayChez1]

What Gulf Stream coach do you have? On my Scenic Cruiser on that particular compartment where the water heater is located there are three other compartments you can get in so that you can work on the lock from the inside.
If not, then you have got some real problems and might have to drill a hole where the key goes in in order to lift the lock. You might want to try a lock smith before drilling and get some expert advice.
I have had a couple of lock failures before, but I was able to get to them from the opposite side. I learned real quick never to slam the compartment doors down. They have a pot metal rocker inside that breaks real easy. When closing the doors now I just bring them down real easy and then just give them a tap.
Give more information as to the type of coach you have and maybe somebody can help you out.