Yesterday I took the loco apart again and checked everything.  It seems the reverse issue was caused when I inadvertently moved the reverse switch when the shell was off.  I decided to move the ground wire to the contact on top of the rear weight (away from the circuit board).  Now the LED works and the locomotive seems to be running fine.  I am having trouble getting the rear two screws to catch their threads in the shell though.  Any suggestions?  Thanks again.