@VitaminM I use 91% ISO from the dollar store.
I fill up a small Tostitos salsa jar just above the cooling chamber parts.
I let it soak for about an hour, periodically shaking it.
Cooling chamber looks like new!
Here is the ISO after cleaning.
I sometimes use this same method to reclaim my oil. To reclaim it, either vacuum purge it, or put it in a 6x6 pyrex dish with a fan on top blowing away from the dish.
***make sure to do this in a well ventilated area***
Wait at least 2 days (or until ISO is completely evaporated) and scrape up the reclaim with a Skilletool or razorblade and put it in a dab dish or on parchment paper (never use wax paper it has paraffin in it).
The higher the grade of ISO the less water in it (IE 91% ISO has 9% water) The lower the ISO rating the more water is in it. It will still work, just takes longer.
You should be able to find 91% ISO at most dollar stores, or something close to it.
This method has always worked great for me.
Hope this helps!