Originally Posted by JillyIsJustKidding
Just clean it really good again. My KM is brass cored and I go through this all the time. Just get a mixture of lemon juice/water/a small amount of dishwashing soap and run it through the stem and just clean it out really good with those pipe scrubbers
yep lemon juice should do the trick, the acidity will remove the tarnish for awhile, till it builds up again, its just oxidation of the brass, its natural for it to occur.