I solved my own problem:
I found that the FermWrap Heater (sold widely for $30) tended to come undone easily.
I was able to repair mine by taking apart the wire clip insulator that had come undone, reattaching the clip and reinsulating the clip with “liquid electrical tape” ($5.00 at the local hardware store). A thorough discussion of how to repair/build your own "FermWrap" heater is available on the web ( http://www.arbreptiles.com/cages/flexwire.shtml
). The flex-tape (heating element) sells for $3.50 a foot at several places on the web (e.g., http://www.reptilebasics.com/11-flexwatt-heat-tape.html
)as does the $5.00 wire clip insulator (e.g., http://www.reptilebasics.com/wire-clip-insulator-set.html