Dogbert's Stepper Extruder Cooler Plus Filament Tube Cooler

I've been struggling with PLA and have three or four almost full rolls that won't extrude. Before completing Dogbert's stepper cooler mod on my one Up and two Afinia printers I added a feature to the stepper cap. I made an air channel that can be opened or closed that blows on the metal filament tube above the heater block. If it doesn't make a difference for cooling or causes other issues by blowing hot air around the nozzle it's easy to turn off. I also cored out some features to minimize need