Koehler lamp help

I have a PERMISSIBLE FLAME SAFTY LAMP ,APPROVAL NO 209
ISSUED TO THE KOEHLER MFG. CO.MARLBORO MASS.USA
.It was given to me by my father on his passing and it was given
to him about 15 to 20 years ago from the ARMY and NAVY VETS mens club he
belonged to as a gift for his contrabution to the running of the club and being
a past presedent and a long time founding menber of UNIT NO. 283.
I would like to make it operational as it is complete but is in used condition
with scratches /dings and a bend in the top plate where the hook for hanging the lamp is .
I do not know how it comes apart or what type of fuel it uses .There is a wick in it and it
moves up and down and there is a turn type handle on the bottom which unscrews and
has a spring behind it.This is the flint mech.
The base unscrews about 1/4 of an inch then stops like it hits a stop
but can not go any further, I have tried to pull the bottom part away from the upper pc where
it seems to unscrew but can not seperate it at all and I do not want to force it.
Can you help me out please ..
Any info you can supply me with would be greatly appreciated , and maybe you could tell me
its approx value as I plan on giving it to my son in a year or two .
Thank You


Robert Hart