[Dan Heim]

Thanks for the tips. You have an incredibly valuable website for learning expressions. Been there often. After reading your comments about frequency I tried the following:

FH = random(1,3); // assigns random horizontal frequency
FV = random(1,3); // assigns random vertical frequency
WH = value + wiggle(FH,1); // horizontal wiggle value in percent
WV = value + wiggle(FV,1); // vertical wiggle value in percent
[WH[0],WV[1]] // this line assigns separate values to the horizontal and vertical scales

That fixed the problem, and the shape is now fluctuating in scale in a way that simulates what I saw in the sky. No more divergence from original size near the end of the comp.

I suspect what happened originally might have been a “random walk” away from the original values that somehow accumulated positive changes. Perhaps in a longer comp things may have eventually returned to normal. Not sure. But what I have now does the trick. And I didn’t need to integrate. Thanks again!