I replaced the battery in my 2008 430 Scuderia and the factory charger doesn't seem to be charging the new Optima 34-R battery. The battery I replaced was an Interstate MTP-91. Is there a compatibility issue or might the factory charger have given up the ghost? Is there a way to test if the charger is still functional? It plugs in and shows green but the green indicator light is flickering a little. It didn't do that before the replacement. Suggestions welcomed.