Converter Voltage Output.

Ok went out for 4 days and late last night 12 volt power issues. Checked voltage to convert 119 volts from shore power to converter. 10.46 volts coming out.I assume converter is Kaput!! Fuses looked good and showed continuety I do not know what size it is , it probably original to mo ho, what do I replace it with. Should I increase amp size when I do so. Battery is brand new and showed 12.86 volts before heading out. It is now down to 10. something volts. I know that this works wonders on a new battery, I just got in a bind and didn't have a portable charger with me. We are back home now and have charger on battery. This outing was a shakedown since we haven't been out in a while and we were having other Issues with coach as posted last few weeks. So what is a good brand to look for and what else do I need to know about converters.
Thanks again Guys!