A few years ago I thought we had a Converter failure. It was mounted behind the rear bulkhead in the basement, so pulled the wall to check and found the plug for the Converter had work loose from it's socket (our converter was a stand-a-lone unit and just plugged into a standard duplex outlet).
Another possible issue is the Battery Cutoff switch, if in the wrong position you won't charge the batteries, or if the connections are loose you can get the same issue.
Just giving you a couple of other things to check before jumping on a new converter.