You've gotta pay attention to what the wood looks like as you are drilling. Were the shavings white? Did the drill bit feel like it hit a hollow spot?
Get a small probe and poke around in there to see if it feels solid or punky.
You could also try injecting just water into the same hole a few times. If a few injections later there is still no resistance, its probably a hollow spot.
Get a small probe and poke around in there to see if it feels solid or punky.
You could also try injecting just water into the same hole a few times. If a few injections later there is still no resistance, its probably a hollow spot.