I have a MTH PS3 Union Pacific FEF Northern (20-3535) that I bought in 2015 and has worked perfectly up until now. The only issue I have with it is the marker lights now intensify its brightness as the engine chuffs. So if the engine is at a slow chuff, the marker lights will intensify to the timing of the chuff and the same is true for higher speeds. While the engine stands still the marker lights are completely normal. This is my only engine that does this and I checked my track which is clean.
Any advice or ideas would be appreciated. Thanks everyone!