I finally found some time to get all this up and running again. I bought a new 1TB drive, reflashed the Slug with uNSLUng 5.5, formatted the drive, Unlusng to disk 1, and got exactly the same result as before… no IPKG functionality. So I bit the bullet, reformatted the drive, then reflashed the slug with 6.10. I was a bit disheartened to see the web interface report the 1TB drive as only 6MB with 5% free space, but I pressed on and Unslung it anyway. It now works perfectly. 1696 is back up and running and I left it copying all my music back over this morning.