This is likely not a signal issue but a power interruption in the tender.
Legacy locomotives from made about 2011 on are extremely sensative to dirty track and/or pickup rollers. Some models are worse than others.
1. Clean your track.
Even though it appears clean it may not. If its been awhile use mild abrasive block like a "Brite Boy" or Lionels track cleaning eraser , then wipe it down with a paper towel with 91% isopropyl alcohol on it. A paper towel leaves no lint.
2. Clean pickup rollers. Same as track, although in my experience the alcohol is enough.
3. A drop of conductive lube on the pickup roller pins can also help.