Lee 20-pound furnace not getting as hot

[NuJudge]

I was casting bullets on Friday (about 35F outside), and even with my 20-pound Lee furnace turned all the way up I was having problems with cold Lead every time I'd add back a couple sprues from the 6-cavity mold I was casting with. I was using Wheelweight scrap with a good bit of Tin. I was operating a 10-pound Lee furnace also, mostly as a melter, and it did not have these problems.

When a Lee 20-pound furnace does this, is it about to fail, and is this something I can fix myself?

[imashooter2]

Thermostat. Replace or repair (2nd page, starting at post 27):

http://castboolits.gunloads.com/showthread.php?t=7204&page=2

Post 34 gives final dimension of my bending.

[lwknight]

If the mold heater is cycling then it is the temp control. If its staying on all the time and still cant get up to temp its because you got too much cold air blowing across it.
It only has a 700 watt heater and a little breeze will carry away too much heat unless you leave ash or something on the melt as an insulation.

[Bloodman14]

Check out your heating element. I had the same problem. Lee has heaters for $11.00.

[markinalpine]

I cut a triangle shaped wedge out of the edge of a coffee can lid to fit around the valve mechanism on top of my Lee 4-20 melter to keep heat loss down. The other notch is to allow my fluxing spoon to fit through. The plastic lid in back is just there for contrast.
NOTE: I have one of those "sidewinder" can openers, that cuts from the side, and leaves a smooth edge. The cut off end fits back like a lid, although it is loose, not airtight or anything.
Mark :coffeecom