The leads go all the way through and the inside of the hole is plated to attach to traces on each of 4 (or more) layers. Some guy calling himself 'bw' says just pull of the caps and re-drill the holes.He's flat out wrong if he's serious and not particularly funny if he isn't. If you're rich, a Metcal soldering / desoldering system would be just the ticket. Less better off a Metcal soldering iron and an Edsyn Soldapullt can do amazingly well. Still less well off a Weller temperature controlled iron (I prefer the magnastat units) and the Edsyn can do well. I wouldn't try it with non-temp controlled irons. Regardless of what 'bw' says, do NOT use drills. The Metcal STTC-126 tip is excellent for cleaning out even the most stubborn hole. Point the tip into the hole (it may take a second or 2 to heat it) pull back a hair and 'vacuum' it with the Edsyn. I've done it thousands of times. While Mike Terrell may have had bad experiences with eBay, I bought 8 Metcal systems there with no problems.
G=B2