Polar express smoke plunger

First stop is perhaps a new plunger.  I've also run across a couple of smoke units where the fit was too tight and there was no fixing them, so they got replaced.

try this cure for polar express plungers sticking at top of smoke chamber

insert a finger in open area of plunger to hold it now wrap sand paper around plunger and sand in a circular motion a few times then see if plunger will go all the way up without getting stuck.

once you can do that reassemble smoke unit and enjoy.

i myself had opposite issue it was to loose and had to use 0.10 styrene sheet to enlarge it and then sanded it to fit.

hope this helps you 

I noticed the lever that pushes the piston up is usually made at an angle that tips the piston sideways a little on the upstroke resulting in binding.   You can take it apart and bend the lever part that sits right under the piston so it pushes it up straight with no binding.

When I take it apart it slides up and down smoothly .  I'm going to try to bend the bar so it goes up and down straight. I think it might be an angle problem. I will also try the sand paper. Thanks for the tips

These Polar Express engines have a sticking plunger problem. They are too loose and stick because of the angle Train Nut posted. CAREFUL with bending the smoke lever! They don't bend easily like a postwar one, it is likely to break. Also try stretching the return spring.