Grundfos UPS2 pump rpm

Having problems with downstairs radiators not warming up. Have used Sentinel X400 to clean system, left in 4 days and drained twice. Have now fitted Grundfos UPS2 pump in place of our 38 year old Grundfos super 4. The clattering and banging is dreadful! Have tried removing venting screw and spinning the pump. The pump seems to spin about once per second. The old pump spun continuously, would spin the screwdriver out of your hand! Is the pump too slow? Any other ideas?

 

Turns out that the problem was the pump wasn't connected to 240v power supply, should have taken a photo of original wiring!