I have a lionel 4-12-2 with the whistle steam that has a fill hole in one of its domes with the rubber plug that keeps the hole from leaking, Just recently the smoke started leaking out of that hole at a surprising rate yet the rubber plug still is on the hole, I am not sure if these need replacing every so often cause the engine is over 7 years old at this point. Was wondering if anyone has encountered this and if they found a fix.
video is attached showing the rate at which smoke leaks and that the rubber plug is still present.
Update this was fixed by putting a drop of smoke fluid on the o ring and its brass fitting.