yes, I had the same probem on my plexi. Nik sent me some replacements and I actually changed it out tonight. the issue is that these indicators dont like and can't take a power surge. Nik wrote that he is investigating another design that will not have this issue.
simple enough to change out, drain the filter caps first.
What did the replacements exist of? Another led or a bulb?
I'm still building the amp, What whould be the correct way to install the LED? In parralel with the heater (if that's true
no wonder it breaks )