Had a WD2500JB (P/N: WD2500JB-00REA0) that was part of an external USB enclosure (WD2500I032-001) that would not turn on. HD board was discolored, and upon using a T8 TORX wrench, found that the grey foam padding was also discolored around several chips.
Following advice in this forum and others, I found a HD on ebay, mfg on as close a date to mine as possible (HD boards go through several revisions as more units are mfg and sold). $60 shipped for a 250GB drive (no enclosure).
When it arrived I desoldered both U12 chips (big solder globs across both rows of pins, then alternated heat and pried up). Cleaned up pins of old U12. Used desoldering braid to clean new board. Then: old U12 -> new board -> old HD. Before screwing back in, I tested continuity of my soldering job on each pin with the diode setting on my cheapo meter. Powered on and was recognized right away. I'm watching all my data stream off it as I'm typing this. I'll have detailed pictures at
http://picasaweb.google.com/gr8horizon$60 saved 200 GB of data. Maybe I'll pay another $60 for a backup drive

This also makes me consider always buying two hard drives at the same time so I have one for just this kind of occasion. Don't be afraid of surface mount components; I actually used a huge RadioShack 40W iron. Just practice a ton on any old piece of equipment... or your cell for that matter... that's what your extended warranty's for, right?