Heather, in addition to the info I listed above, and Jeffrey's support of Master's teachings on the bangles, below is additional information from Yogananda himself. I've been working on editing the original message board, and I don't remember any indepth discussion about the bangles.Astrological Bangles: Letter from Yogananda to Rajarsi Janakananda
From a letter written by Paramhansa Yogananda to his closest disciple, Rajarsi Janakananda:
"According to astrological laws to do away with all bad influences of planets, there is nothing better than a bangle. Each two bodies of the universe attract. When this adhesive power of the bodily cells becomes lax with the advance of age, the planetary pull becomes stronger, causing more laxity of cells, inviting disease and the mind to disturbance.
"The bangle and its combination of metal as fixed by the Rishis emanate electronic ray (unseen to human eyes) which counteracts all planetary vibrations. Just as a lightning rod is affixed to a house to absorb the falling thunder and lightning, so the bangle is a lightning rod to absorb the ferocity of bad planetary rays falling on the body, when disease attacks as bad karma.
"Besides, I heard Master say many times that satan creates in the mind of the bangle wearer the impulse to take the bangle off, so uninterruptedly he could punish them through the instrument of bad karma of past lives. I remember definite instances of cases who almost could not wear the bangle as the arm rotted under it.
"One person had to change the position of the bangle three or four times. He was cured of paralysis and some kind of fits. The bangle will also modify and lessen any wrong influence on business. Sometimes to take the bangle off when one needs to, even in that moment, it is also dangerous. I write this only to emphasize the laws of electronic vibrations which God created and the Rishis discovered to counteract the eveil planetary influence on the human body."http://www.astrological-bangles.com/bangles/html/b_book.html
From the book A Paramhansa Yogananda Trilogy of Divine Love, by Sri Durga Mata
Copyright 1992 by Joan Wight
More information is availabe in the Astrologlical Bangles Booklet by the Ananda member who makes them, and which you can read here: http://www.astrological-bangles.com/bangles/html/b_book.html
Hope this helps.