CMM1000, "type" unknown. This is a first ten mower I have had for >15 years. Had to replace batteries once previously. I have newer B&D batteries in the mower. Charge light says green but when I run it, the gauge indicates yellow for a few minutes, then goes to red and will not cut grass at all well (as you would expect). Suggests charging is not actually occurring. Looking for troubleshooting guides or past experiences that may help diagnose. Would like to fix before the new batteries are beyond charging...