Can anybody tell me how to (further) check my VAWT charge controller for malfunctioning?

I have installed a Flexcharge NC25A-12 Charge Controller and an SE440 regulator in line between my VAWT turbine and its rectifier and the 1000 amp inverter. The turbine and controls charge four Trojan 105, six volt, batteries which are hooked in series parallel (two each in parallel, the parallels hooked in series). The turbine is a heavily modified Lenz-2 (vertical axis, three blades with spring-loaded furling & angle of attack control). It generates 108 to 140 Watts (nine amps at twelve volts to ten amps at fourteen volts) at wind speeds of fifteen to twenty five miles per hour.

Nevertheless, I'm not able to charge the batteries. I think the Flexcharge charge controller is stuck, that inasmuch as the controller’s "Multi Function Indicator" function does show when batteries are low, when voltage from the system is low, and when charging is occurring (flashing and steady green light), but has never shown "divert" (to a heat sink). More, I have never been able to get the batteries to hold anything close to their individual 225-250 amp-hour rating. It's beginning to look like the batteries, purchased new originally, have sulfated on account of the charge controller panel not working.

I note in using my multimeters that the cable at the heat sink indicates 2.85 volts, even when the batteries are down to 11.9 volts, and when the charge controller is not indicating "divert." When, moreover, an external battery charger (the automotive kind) is hooked in line and in lieu of the wind turbine and rectifier (these being disconnected from the controller, regulator, batteries, and dump load), the batteries indicate full charge on both hand-held multimeters and turbine system voltmeter and ammeter, but the charge controller does not indicate “divert” to the dump load heaters.

Any ideas will be much appreciated. Thanks!