some E6400 keyboard key caps sometimes fail till physical reset

The keyboard on my Dell Latitude E6400 laptop sometimes fails. When it does, usually 1234 7890 End and Windows logo key caps operate normally but have no effect while letter keys and 5 and 6 work fully; other keys vary or were untested. Plugging in a USB keyboard is a kludgy solution.

I reset the built-in keyboard (removing the LED cover and two bolts or screws, pulling it out, maybe rubbing or banging edges especially the connector near the space bar, and returning it) and that usually solves the problem. Lately, I'm finding that sleep for hours may solve it, too. Even sleepless nonuse for hours solved it once. Maybe heat is a factor; I don't seem to have the problem outdoors in any season. One recovery was spontaneous.

This was happening every couple of months or so. Now, on some days, it can happen a couple of times in a day and then not happen for a while.

Is there something I should do? Is a cause likely known?

Possibly related: https://www.dell.com/community/Laptops-General-Read-Only/Dell-Latitude-E6400-Some-Keys-Not-Working/m-p/4315785