If you have a machine that Take Control says is not installed or a heartbeat is not detected, if you can get to it with other means, perform the following. I had to open a case with Solarwinds but this does work.
1. Click on the device name in N-Central console. Go to Settings > Properties > Uncheck Install Take Control
2. On the same device, delete this folder C:\Program Files (x86)\BeAnywhere Support Express\GetSupportService_N-Central
3. Click on the device name in N-Central console. Go to Settings > Properties > Check Install Take Control