Well, with a totally full iHP-140 and with matters being painful everytime I purchased a new CD (having to decide, what music to delete from the player, to add new music onto it), I had to decide: mod the player or replace it.
Not yet prepared to part with the player, I bit the bullet, purchased a 60 gb drive offered for sale here, and installed it. Voila--I have now joined the ranks of others and am the proud owner of a new iHP-160!
I am amazed--I now how 17 gb of space free on my player (compared to nothing before)! I keep on looking at that and feel content--that's enough to last me for another 2-3 years.
Installation went fine (no screws got lost or parts got broken--thanks for the warnings, here, on not screwing the screws too tightly!), although the guts of my player may not have had some of the rubber protection that other players have had, from past descriptions--I kept on looking for that rubber to remove, to install the new drive. Putting the new drive in was a piece of cake--just wriggle the old out and wriggle the new in. The formatting for the new drive was a bit experimental: the formatting software, SwissKnife (needed for larger FAT32 partitions), glitched up on me when I tried to read its Help screen as it was doing its formatting job--I learned never to touch it while it is working. I was able to fix the glitch, which stopped SwissKnife from completing a format despite repeated attempts, by running a basic NTFS format and then re-running a SwissKnife FAT32 format--without touching the computer as it worked.
With the newly-found space, I already have started filling it.
Happily so.
At any rate, eminently do-able by a non-techie non-engineer.
Many thanks (really, really, really!) to those who created the Wiki instructions here on swapping in a new hard drive, and to those others who have posted instructions and photos here, especially NPswimdude500 and Paperman23--they gave great comfort and assistance. And to Kramerica, for selling me the drive, as well as MisticAudio for having the needed torx screwdriver available!