Boiler making intermittent noises (video included with sound)

scuava

I have an electric boiler which has started making noises intermittently, which sound like it could be the pump into it.
See this video to illustrate the noise it makes (the sound started up at the 17 seconds mark):

https://imgur.com/a/Za7odgl

It seems to do this every few minutes, occasionally very often, other times more rarely.

This doesn't seem to cause any issues and I still have hot water working as normal. But I'm worried it may be a sign of a bigger problem, and the noise is slightly annoying.

I've read up on the internet but can't seem to identify the issue exactly.

Can anyone advise what the issue might be, and how to fix it please? Or whether I need a plumber to come and check it properly.

Thanks!