I did a lot of SWLing in the early days and heard the woodpecker many times. For me, it was mostly just an annoying popping signal like a really bad ignition system. But it was forgotten about as soon as it went away. Then, in 1980, I was contracted to the Air Force and moved to Germany for a few years. While I was living in Germany, I operated CW only as DA2EU. You have not idea how powerful the woodpecker signal was, until you were up close and personal.
If you were unfortunate to be wearing head phones, it felt like someone was running a spike through your ears. I would have sworn that the headphones were blown, but I guess the radio wasn't that powerful. When the woodpecker came on line, you couldn't get the phones off fast enough and turn down the radio. Even with the audio and RF gains at minimum, you could still hear it. It didn't matter what band you were on. But, when it stopped transmitting, it was forgotten right away. The band was back in operation within 5 minutes. It was like nothing ever happened.
A lot of operators were convinced, and still are, that their attempts at sending strings of "dots" or "dashes" somehow caused the woodpecker to go off the air. While I admire their efforts, most didn't realize what they were up against. Even at 1KW, they might have shown up as very low lever signal in the noise, but that's it. IMHO, whatever they did had no effect on the woodpecker's operation.