Welcome to the forum.
Any RV repair shop can help you out. There are some internet vendors that sell power converters, too. There's probably a good chance that the model number (maybe even the brand) you want has been discontinued which means if you can't find one, you'll have to try to get one with similar electrical specs, as well as similar physical size so you can put it into the same space without too much effort at making it fit into the existing space. What's the brand name? You might have to call around and say, "I need a replacement for my X brand model 930 power converter. What do you have that's the same size (physical dimensions or smaller) and electrical capacity?"
Good luck!