Well you won't be soldering on the HDD - but you will be soldeing on the main and/or daugher boards, but I know whay you mean - the thought makes me nervous and I used to work on disk drive heads... (I think it's because it's *MY* player)
Linus* did promise to post some instructions on the fix when he got a chance - maybe if you search for the thread and ask really nicely he may be able to find the time to post some information that you could use or show to someone with a soldeing iron.
Did you try Mistic River ? - there are many H1x0 owners over there and this fault won't be a RockBox problem...
EDIT: * Well I must be going mad - I was sure it was Linus but I've just done a search session and found several message where he said he's solved H1x0s with soldering the USB/HDD daughter board, I can't be sure if it is the 4 locator pegs that join the boards (if they come apart the connectors will stop connecting) or is its the actual soldeing of the connectors to the boards. My memory is that whoever it was said that next time they'd take pictures and write up the repair but I can't find it now...
Further Edit: Ok, I'm not losing it - just not so good at searching... it was here
http://forums.rockbox.org/index.php?topic=7687.15 but obviously he hasn't had time (I don't know how these gusy found time to do RockBox, but I'm glad they did!)
Yet more edit (several hour later): I've searched on Mistic River and found this
http://www.misticriver.net/showthread.php?t=45641 and this
http://www.misticriver.net/showthread.php?t=54835 there are several more