The lid is made of a top and bottom half which must be split to clean out the internal mechanism. This is achieved inserting and twisting a butter knife (blue arrow). The knife should be inserted between the upper side of the lid and the flexible seal. Quite a bit of force is needed as it's held by four plastic clips.

Other kettle lids may be similar but check there are no screws before using too much force.

Once open, the three internal plastic parts (don't loose the spring) can be removed and cleaned with, say, white vinegar and toothbrush. When clean, reassemble and clip the two halves of the lid back together. Easier done with lid open.

It may be tempting to put grease on the internal mechanism, but only do so if absolutely necessary as grease eventually attracts dirt. My lid mechanism worked very well with no lubricant.

Comment. It may be possible to clean the lid without cleaving it in two, by submerging it up-side-down in warm vinegar (+50%water) for say an hour. I haven't tried this. You don't want to get vinegar inside the handle to the electrics as this may cause corrosion. And of course everything must be dry before turning on.

If you find cleaning the lid this way works it might be worth adding a comment to this post with any problems encountered, such as difficulty in rinsing away the vinegar smell as there are only small holes liquid can get through (by sprung-loaded latches).