Juwel Heating Element Possibly Not Working

I have a funny feeling the thermostat in my Juwel heater may be kaput.  The water's sitting at 33 degrees no matter where I position the twisty control.  It's around 12 years old and had sat in my garage for 7 years.  I started the tank up last week after a hiatus, so no fish to worry about, but the question of why it's so darn warm is vexing me.  I don't even know which way to twist the control to decrease the temperature, as it sat untouched in the tank previously and kept the water spot-on without requiring adjustment.

Does anyone have any ideas?
m.d.

If it is an older version of the heater it should have + and - on the top with arrows pointing which way to turn it. It takes something like 12 clicks to go from one extreme to the other if I remember correctly. When my fish got whitespot I had to turn the heater up and had to count the clicks so I knew how many to turn it back afterwards.

But I agree that a new heater is the best option. You can't risk a possibly malfunctioning one once you have fish.
Heaters are the one piece of equipment where it is better to go for a good, if expensive, brand. Cheap far east imports are more likely to fail than good makes.

If you want to put it in the filter compartment, that's fine, at least you'll know it will fit 

I don't know what juwel you have but i have a Rio 180 and when i first brought the tank' The first thing i done was buy a new heater as i read the ones they give you is a 100w.

I brought a Visi Therm Aquarium heater  200w  and it fits and works fine.

Shopping is often the answer to a problem. 

Fingers crossed that your new heater works perfectly.