VIP Persistence

Thanks for the "Action on Service Down" tip (real D'oh! moment there). However, we're having trouble getting the LTM to actually Reselect. We've tried the Disabled/Forced Down node settings, as well as writing an ECV that allows us to flip the nodes in/out of service. But in all of these cases, we're still seeing HTTP connections to the out-of-service pool member (as viewed in the Pool statistics) for quite a while (hours, in some cases). How can we *force* the Reselection to happen on demand, moving those connections over to a different Pool member?