My A1181 just started displaying "overscan", parts of image missing.

I've got a modestly old MacBook A1181, the model that had a dozen siblings with slightly different features but shared the same designation.

Overnight, without any fuss or muss, the display went into an "overscan" mode. In other words, the image on the actual screen is only about 80 percent of the full picture and

about 20 pct is "off the edges" (numbers nominal).

I can still bring them up by sliding the window, so to speak, around, but that's very unfriendly

Any ideas how to reset this? I tried a bunch of tricks, including reinitializing the PRAM [a]. No good.

Thanks muchly.

[a] rebooting while holding down command-option-P-R