With the tires on my mountain bike not holding air, I had a choice: take it back to the shop, or take up arms against a sea of troubles. (Or, rather, a dwindling puddle of Stan's Sealant.)
The usual way of adding more sealant is to pull a bit of the tire bead off the rim, pour in some sealant, and then use an air compressor to re-mount the tire. But I don't have an air compressor.
Luckily, there's an alternative for tires that are already mounted: remove the valve core, and inject the sealant straight into the tire through the valve body.
Seemed simple enough. Worth a shot.
So I stopped by the shop today, and bought what I need to tackle the problem myself.continued