I would strongly suggest a new, recent model converter rather than trying to find anything like the original equipment.
Best Converter would be an excellent source for a new one. They have great pre- and post-sales support so don't be afraid to use the "Ask Randy" button anything.
My suggestion would be a WFCO model WF-8715 (15 amps) or WF-8725 (25 amps) for $100.
I replaced an Elixir 12 with a WF-8715 and really liked the upgrade to a three-stage smart charger.
Of course, more capacity for circuits and charging can be found in the WF-8935 but you're into $150 at that point.