firstly ditch the 75 watt bulb, 25 - 40 max, the bulb should sit on the ring leaving the bulb fitting hanging down, thats the correct way
There is no way a classic 40w golf bulb would fit in it: the ring is far too large.
With the 75w the lamp run normaly but the base is very hot (no kidding :-) )
I noticed the wax is never solid, even when cold.
Any idea about the bottle cap?
it would taken a standard 40watt bulb NOT golf ball size, just like what the orig crestworth telstar bases used, and the early bottles used to use a liquidy wax like crestworth used to use first, i really recommend you dont run it with the 75watt bulb, not sure about the bottle top, ones ive seen always had a metal screw cap with a plasticy bung in em, but im not expert on hunter sata-lites with bottle tops,
only way you'll get around with a small size bulb is to modify where the bulb sits
I didn't knew about normal size 40w.
I will try to find one. But looking at the 75w bulb (dust on it) it has been here for a long time, and wax still working well so no damage here.