I own one of the PM versions with the PE tender. Mine blinked for awhile and eventually went out.
I contacted Lionel when my loco was still under warranty .
Theres was an issue with the LED, and they sent out a new bulb and wire harness .
I plugged in the replacement and never had the issue again.
Heres the replacement on the parts list for your 11146 it shows "out of stock".
Heres the replacement for my 11204 PE tender, its still in stock and shows a PCB added. I believe its the PCB that fixed the issue:
Either way I'd call Lionel, or possibly get in touch with Mike Reagan to verify the correct replacement, as these were produced under his watch.