Hi, hopefully I can get some advice on if my electricity meter has a problem or not. Currently my electricity meter makes a low-frequency humming / rumbling sound as the counter disc rotates under the numerical readout. Sometimes it's quite loud but at other times it makes next to no noise at all and it doesn't seem to depend on the amount of electricity that I'm using. The meter in the cupboard under the stairs and is sealed by wirelocks, presumably from the electricy board with a 'certified 1997' sticker on it. I know that I can't do anything to the meter but was wondering if this was normal or if I should get an engineer from the electricty board to come and have a look at it. Thanks!