My build of 11 LE's last year had your same issue on some of the LE's. I had 5 of the 22 485 chips that acted that way. It did not affect the data at all.Putting a scope on the output of a normal 485 chip without a DMX signal shows the output is high or at the 5 volt level. on the 5 chips that would turn the DATA LED on the output would be low or < .5 volts.Next adding the DMX signal to the LE to both chips did not make a difference in the DMX signal pattern.As to the LED dimming slightly that would be normal on the 485 chips that keep the DATA LED on. that's because adding the DMX signal now is turning the LED off and on very fast with the 512 channel data stream 44 times a second.