My understanding is there are different versions of the smoke unit, basically 5v and 18v. If you have an 18v version then it will not smoke much unless you are running your loco fast - or DCC. Are you running DC?
there are actually 3 versions used by LGB, 5 volts, 18 volts and 24 volts. The 5 volt units are driven from a regulator that varies from loco to loco. Some of them actually use 5 volts and the smoke is a little weak. Others have bumped the regulator to 6.4 volts and the 5 volt units smoke much better, about the same as an 18 volt unit that is really running at 18 volts.
The units are actually made for LGB by Seuthe who offers even more types.
What kind of loco is it? If it is regulated unit, then it should run pretty well at lower voltages. If it is one of the non-regulated units, you will have to get the loco moving right along to get any reasonable smoke.
the first thing is fill-not more tha 1/3 -1/2 -some do really well with just 4-5 drops
here are my thoughts
there are variations in seuthe smoke units -some smoke better than others
what i think i notice is that old analoge PRE decoder ready engines seem to smoke better than decoder ready engines
the few LGB engines i have with decoders (i run analog) smoke well -and smoke when almost standing still -this i think is a function of programming the the voltage to the smoke unit-in my case my decoder engines are the porters-which i think shipped with 5v smoke units-not 18 or 24 v
so these may be getting direct track voltage -and whcih is why they smoke really well -and why older one had burned out before i figured this out-i now run porters at very low voltage
the decoder ready engines seem to get less voltage to the smoke units via the cirucitry (only my guesstimate) -i find that if i run at about 10-12 volts i get 'normal" smoke
yet on my Chinese drg forney i have to run fast (10-12v) to get full ights and smoke-
on my Chinese wild west forneys (2) i can run about 7v and get bright light and great smoke-
my Chinese 2-4-0 and 0-4-0 US styles -both smoke great also at lower voltage
my german forneys with sound smoke profuseely-non deoder
my decoder ready rack steam smokes politely at best -same with my green spremberger-yet my older black spremberger smoke profusely
so im guessing the decoder circuitry -when in ananlog mode -chokes the voltage to the smoke unit a bit-but it may be more because even at full voltage (18-24) they still have lesser output than what i would call normal-so maybe its a programming issue-5 volts not enough-nor 6 -maybe 7???maybe it varies with every unit
yet on my genesis (doecoder ready) to which i added a smoke unit - it smokes great
so it may be nothing - other than variations in seuthe production
running DCC it should smoke well if its proeprly programmed and getting full voltage
and it may well be that depending on when the engine was built -early 'transitionial' decoder models may not have been quite properly outfitted or programmed-i really cant tell-