No reason on the planet to replace the smoke unit for simple maintenance issues, you'll just be doing the same thing soon with the replacement.
I would replace the smoke resistor, that one has the 6 ohm resistor, Lionel recommends replacing that with the 8 ohm resistor as the 6 ohm was taking out the smoke regulator module prematurely.
I suggest buying real smoke wick and a smoke resistor. If you're getting no heat to the smoke unit, you may have to replace the smoke regulator, it could have crapped out. It actually doesn't look like the picture below, it's in a small heatshrink encased package.
