Spot Lights - Power drops

[Loftus]

After 5 years of no problems with my kitchen sunken spot lights (9), two of them become dimmer for a few seconds, every now and again before returning to normal brightness.

Any ideas why this is happening, and how can I correct it?

[professorgbr]

look for poor arcing electrical connections starting with the good light that may feed them

[Loftus]

Would this be a job for an electrician then?

[nirru]

yes and no depends how confident u are. isolate the spotlights, check and tighten the every connection.

[aaronj]

I had this on a job a few months back and it was a transformer. This will only be the case if you've got one transformer for more than one downlight. You may even have mains voltage lights(no transformers) in which case ignore this.
You can tell this without taking the light fitting out by the light bulbs/lamps you use they'll be either GU10s-no transformer or MR16's-transformed.