If you have oil-fired central heating...

[Scrunchcake]

...you might be able to answer my question.

We've just moved into a house that has an oil-fired boiler for the water and heating - all new to me and in this cold weather I'm trying to learn fast!

There's a little plug-in wireless gauge (a Watchman Plus, fairly old I think) that the previous owner said to keep an eye on for the oil level but it's not working accurately. Based on the light and display I think we need a new power tube and to check if there's liquid in the bund. My question is, do those sound like things I'd be able to do myself as the householder or should i be getting a professional in? And if the latter, which professional? Same people as would service the boiler itself?

Grateful for any wisdom and help you can offer here 😊

We just pay slightly more per litre than if we had shopped around. We don't pay a yearly payment, but we pay a monthly direct debit for our oil, and if we are in credit, they pay us interest on what we have in our account. So now the DCs aren't at home we don't use so much oil, but pay the same monthly payment and the interest we get cancels out the few pence per litre more that we pay for the oil.
Hope that makes sense!