Hello #MechanicalkKeyboard, I have an old and loved keyboard with cherry black switches. A few keys, most notably left ctrl, need a "warmup". They won't function out of the box, instead I have to press them intensely for a couple dozen times and then they work again.

What do I need to change/repair to get rid of this behaviour? Is it some kind of cold solder connection or a defect switch or something else? Only affects 2-3 keys, the others are fine.