Hi Richard, finding a new rotating beacon maybe a challenge, one plave to check would be E-Bay I have seen them listed there from time to time. Only other way is if someone has one laying around in a parts room I know I have several but none work or are worth the money it would cost to make them usable. I'm thinking you may have to go to a strobe light or maybe one of the new LED beacons they draw very little current. There is one listed on e bay now here's a link to it.
http://cgi.ebay.com/ebaymotors/AIRCRAFT-ROTATING-BEACON-NOS-P-N-M58085-3_W0QQitemZ220449107171QQcmdZViewItemQQptZMotors_Aviation_Parts_Gear?hash=item3353ca6ce3&_trksid=p4506.c0.m245&_trkparms=65%3A10|39%3A1
