Here is a trouble shooting chart for the 6300. If you don't have that model, the guide should still apply somewhat.
http://www.parallaxpower.com/6300/LinearSeriesBatOvrChg.PDFIf you have another converter model, click it here then find its tech docs.
http://www.parallaxpower.com/Legacy.htmIf you upgrade, do not go to the 7300 or 7400 which are now also by-passed. Parallax has a new series, but they are expensive. Instead you could choose from a PowerMax or PD replacement. Stay away from the Ultra kit too.
http://www.bestconverter.com/