Bad 5th Gen or Harddrive or whole ipod?

Well i have a 5th Gen Classic(5.5 Gen with the 30GB Drive, Model number MK3008GAL) that has had problems since the day i got it. when it comes to only a certian set of songs, the HDD begins to continusly click and the song never starts playing, but the ipod still responds for about 30 seconds. Then it locks up and clicks forever till the batt is drained or i reset it. The drive Smart data Shows it has 671 Reallocated Sectors, 74 pending Sectors, and only 141 PWR on Hours. less than 10,000 Start and Stops. In a Disk reader, shows alot of Found.XXX folders and refuses to format. This is much shorter than my last 5th gen.(lasted 6 years before it go destoryed in a lab accident). Question is, It should be fine i if just replace the HDD correct(i have spares of this Same HDD).