Magnetek 6300Q power converter failure

I have a '99 keystone Sprinter, It is my home, away from home for work. I just had the fridge die,$1500, then went to move & rooms wouldn't come back in, turns out both batteries were dead(I put in new when I bought in 2008) replaced with die hard marine 850 amp, deep cycle sealed @ $200 each. a week later the "check" light came on on the fridge and I find the batteries are down to 9 volts! I am connected to park power & all is fine with it. Got a 110 v battery charger it ran for a day before the light went out. I disconnected from all power, cut & taped both ends of the wire to the (transformer?)under the fuse & breaker box.(its been making alot of "humming" noise). Now the charger seems to carry the weight, but I am afraid to leave for a week or so when I get time to go home. All the internet results seem to tell me that I'm fortunate it lasted this long, but most of the reccomended replacements seem to be out of production as well. Are there any replacement moduals still out there? I really don't want this to be an "end of life" situation.