wouldn't hold air in one side, thought for sure i'd have to rip out and redo the lines.
luckily when airing up one time i heard it leaking, right from the valve stem.
never changed out a valve core, but my local auto parts store had a $5 kit that includes the little tool and extra valve cores. pretty easy to change out, the valve core just screws in like a regular screw. will report back if this doesn't fix the leak.