I have translated many books from German into English. I am working on a project right now that has a rather odd word in it, which is one of those perfect words that very few people seem to know. The German word is "pendeln," which means to swing or sway back and forth as a pendulum. The correct English word is "pendulate," but it is so rarely used that it will very likely look wrong to the reader.

So, I'm looking for a really good substitute for "pendulate."

Vacillate is close, but it carries the baggage of hesitation with it. Fluctuate comes close, as does oscillate. However, none of these is really a perfect substitute for pendulate.

Any help would be greatly appreciated.