How do I test if Circ Pump is knackered?

Hi all,

Siemens SN26T590GB/15.

The dishes don’t get wet. If I open the door whilst it’s running I can briefly see the water just gently spilling out of the bottom arm, which isn’t rotating. I’ve already had the entire thing apart and I could see no obvious problems or blockages with the circulation pump.

The question is, how can I test it to see if it’s actually knackered before buying a new one? Do I need to look harder for a blockage? I took the pump/heater out of the housing but didn’t disconnect the housing from the sump because the clips don’t look like the easy-to-reuse kind. I’m reasonably technically able and have some useful gubbins… multimeter and DC bench power supply, but assume the pump runs on 240V AC, I can make up a test harness but would it be any use? It obviously works a bit or water wouldn’t flow at all, so I’m not sure I’ll learn anything…

Thanks in advance,
Adam