Aristocrat won't flow properly

[pspees]

I have 52 oz lamp (my profile picture) that has started to act up. It will only flow for a couple of hours before either all of the wax sinks to the bottom as one big blob or it will turn into one long column and not break apart for a very long time. The coil appears to be fine and is properly positioned at the bottom and the bulb is a clear 40W. I read somewhere that some of the larger lamps need a reflector of some sort that goes around the light bulb. Could this be the problem? Thanks!

[pspees]

The manufacture date on the bottom says 1999. I just put a frosted bulb in, the wax just started to break up, so far so good. We'll see what happens. Thanks!