If it was working before and your 100% happy it still works then just bleed it with the bleed bolt. If your not sure like I wasn't then spend 20 mins, remove the two bolts and put an electric drill on the shaft and spin it. If I hadn't I would of ended up with a rather more expensive bill than just the new pump.

You could also just run it on a bit of pre mix until oil flows, I did that but it still didn't flow which is why I connected the drill and found for sure it was the pump that was faulty. The other pumps I had flowed oil almost straight away.