Hello,
it is possible there might be a dry spot keeping it from outputting fully. What you can do to try and get it outputting like normal is to get an oral syringe (it's a small syringe used to give to small children or pets medicine) and fill it up with fog juice. From there connect the syringe to the hose found in the fluid tank and remove the filter at the end. Fill the hose with as much fluid as it will take then put the filter back on and move the hose back into the tank. Try running it like that after and you should see improved output.