Is my smoke unit broken?

[Neo Fender]

First: I'm not looking to start a pro/con smoke debate.

I have a 4-6-0 that was part of a Christmas set that my Dad bought for my kids two or three years ago.  The set has < five hours of total running time.  I'm not sure how a good or bad smoke unit should behave, hence my question:  With three or four drops of MTH scented oil, the engine produces what I would say is a moderate amount (at best) of smoke for maybe two minutes (four or five trips around a 25' or so circuit).  When new, I don't recall it making more smoke but a couple of minutes worth doesn't seem very encouraging.  I don't have oil leaking from the engine and flipping it upside down doesn't produce any drips, so I assume I haven't overfilled it. If it's broke, is replacing/repairing it something that I can handle on my own or

Thanks.

[altterrain]

Nope, not broken. Its not much of a smoke unit. You can put a bit more smoke fluid in it though to make it last longer. I think it calls for about 8 drops. The faster you go the more smoke you get.

-Brian