TomDfromCT wrote:
I have over 12,000 reallocs.
Is it possible that not using the "safely remove hardware" or not ejecting the device from iTunes could cause such a problem?
No
If the hard disk is damaged, can it be replaced/repaired by Apple or is it more sensible to just get a new device?
I don't think Apple do a hard disk replacement service as such, but they might offer a refurbished product at a discount over the new price. There are third parties that will do hard drive replacement, or you can attempt to do it yourself. Having replaced batteries in a couple of iPod video aka 5th generation models in the past I can tell you that the hardest part is getting the case open. Almost impossible to do without some damage to the case unless you are skilled, careful, and have the right tools.
A new machine obviously has the benefit of being new. For each of the other appraoches the cost & warranty protection will be different. It is up to you to weigh the options against each other and make a decision as to which suits you best.
tt2