Railking Hudson Sound Issue

This is a PS1 engine. I would check to make sure the tether is properly seated. There could also be a bad solder joint at the tether connections. 

Smoke is independent of board.  It gets track power from engine via switch under engine.  So you need to see if it is getting consistent power.  Does the engine slow down when chuff cuts out?  You say it runs fine?   Doesn't sound like tether issue unless the engine is stopping or slowing down too.

In the manual do a reset 18 and try again for sounds.   But the smoke is separate.

Last are the wheels and pickup rollers clean and lubricated?  Could be intermittent power from dirty wheels and bad pickup rollers. G