Open up the "Monitor Polling Engines" tool located in the Advanced folder in All Programs -> SolarWinds Orion
Click on Poller Load Balancing icon (or use the menu)
Highlight all of your nodes (you will notice they have the old hostname) ((Click the first... scroll to the bottom, hit shift and click the last to highlight all))
Click on Poller - Move Selected Nodes to - and select your new server hostname...
** I did this from memory, but this should get you close** If you need more help, simply call into support, we can walk you through this in about 1 minute.
Thanks and HTH,
Your memory served you well. Got everything over to the renamed poller. Most thanks!