New answers tagged kegs
Liquid nails or rubber cement would work nicely. Make sure that you remove the 'boot' and remove all of the old residue that may be stuck on. I would probably run some coarse grit sandpaper over that afterwards just to create a rough surface for the cement to bind to. That isn't necessary but make sure you clean the area at least.
I've heard liquid nails does a nice job.
I've heard of people using the adhesive for car mouldings to do this. They said its available at most autoparts stores.
I'd suggest marking the root-beer smelling lines as your soda equipment and get new "beer-only" lines. You might be able to get the smell out of the plastic with enough heat and time, but they're cheap materials. All the expensive metal parts that came in contact should be fine. Be sure to consider your keg's seals, it's possible you're getting some aroma ...
PBW + hot water (I believe 140°F is the recommended temp) has always worked for me on stainless steel parts. You may need to replace the plastic parts, i.e. tubing, if line cleaner or PBW doesn't work.
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