You might consider a couple of points that are easy to overlook. First is did you perform the Initialize HDD step? Using the normal remote, go into the Home Menu>Initial Setup>Disc Setup screen, and check to see if the option "Initialize HDD" is shown (the recorder only makes this visible when it needs to be done). If Initialize HDD is available, that means the HDD needs to be formatted to clear the "HDD Is Incorrect" warning, so tell the unit to initialize. If you don't see the Initialize HDD option, something else is causing the error, and you'll need to troubleshoot further.
The HDD itself: where did it come from? Is it new, or taken from a PC? Individual Pioneer recorders have a varying tolerance for repurposed or pre-formatted HDDs: some accept them and initialize them with the Pioneer OS with no hiccups, while others choke on anything but a completely erased HDD. Try attaching the HDD to a PC and use a Linux, Mac or Windows utility to completely erase it: under the format options, choose "none" (no file system of any kind, no partitions). Then put it back in your 640 and try the CPRM match again. Also check the location or presence/absence of the tiny termination plug on the rear of the HDD: some Pioneers work better with no plug, others work better with it in the Cable Select position. Examination of the original HDD is often helpful on this point: unfortunately you don't have it, so may need to experiment.
Another thing to watch out for is the service dvd: make sure you have the correct one for the 640. Like the 550/650 and 560/660, the 640 requires a "Type 2" service i.d. data disc. The version most commonly circulated online is the "Type 1" version GGV1179, designed for the earlier 510 and 520 series. This will not work correctly in the 640, which needs the later GGV1305 or GGV1321 disc. Check to be sure the unit displays "ROM Write OK!" onscreen after running the service DVD, sometimes it flashes "ROM Write NG!" very quickly and you miss it, assuming all went well.
Finally, the last step in the CPRM process is very twitchy with some units. Most are not that particular about the sequence, others are extremely picky and will result in "HDD Err" if it isn't done EXACTLY as follows: after the unit displays "ROM Write OK!" on your TV, remove the service disc from the tray but DO NOT close the tray. Press CLEAR on the service remote, then press the power button on the recorder front panel. The tray will close automatically and the unit will power off. Wait a couple minutes, then turn it back on. It should boot normally with no error display.
The aluminum tape is applied for grounding/shielding purposes: the unit will function without it as long as you re-apply the foam blocks that keep the cabinet cover from touching the internals. It would still be better to buy a roll of the tape and re-apply it as done on the original HDD, however: these recorders can be very sensitive to the slightest HDD glitch, including spurious electrical noise or poor grounding. Since you say this particular 640 came to you without the original HDD, you likely didn't get the foam cabinet-standoff blocks either: at a minimum, you should not connect the unit to power without those blocks. It is remarkably easy to short out and destroy a recorder motherboard by cabinet pressure on one of the internal metallic parts (HDD, DVD, PSU, etc).
Best practice would be to study one of your other Pioneers and apply fresh grounding tape and spacer blocks to the repaired unit to match.
Where did you get your GGV1321 Data Disc, Silent Running? My 450H just started posting an error with the HD message a few days ago after we lost power one night.
Before that it was working great. I bought the unit new in 2007. I found a service remote on eBay so now allI need is the Data Disc. Thanks.
Maybe I should look for a service remove and necessary disks before I need the, while they might be easier to find than later.
Although I mostly use my H640 ad H650 these days (in the living room), my original, 420H purchased after someone here said Costco was selling their inventory is still connected (in a bedroom) and works.
As mentioned by myself and other Pioneer owners in many AVS threads, the key reference site for all things related to Pioneer DVD/HDD recorders is PioneerFaq. If you go to this page at PioneerFaq, you will find links to hard drive replacement instructions for the various model series on the left hand blue column. If you need a Service I.D. Data Disc, make a small PayPal donation to supportATpioneerfaqDOTinfo, with a note requesting which disc you want, and you'll be directed to a clean download link. Donations defray the expenses incurred keeping the site hosted online, and are much appreciated. There were endless versions of the service disc covering dozens of international Pioneer model variants. But since Pioneer stopped making recorders in 2008, it really boils down to just the final versions of the Type 1 and Type 2 service discs.
Models in the x100, x10, x20 and x30 series need a Type 1 disc, the most reliable version being GGV1256. The GGV1302 was the last actual Type 1 disc, but seems impossible to get and offers no real benefit over the GGV1256. The very old GGV1179 should be avoided in favor of the GGV1256. Especially avoid random torrent links you might find to the GGV1179: these are often corrupt or partial disc images. Models in the x40, x50, x60 and LX series require a Type 2 service disc, the last of which was the GGV1321.
The service remote can be difficult or expensive to obtain, depending on the country you live in and which version you buy. The original Pioneer service remotes are long out of production and impossible to find, but generic "clones" are still available in North America. The one that I've used for many years is the Pioneer GGF1381 clone available here for $51.95. Several years after I bought it, Sony began offering their J-609-0-203-A clone, which was bargain priced at under $20. Unfortunately Sony stopped selling it in 2011, but a nice generic clone is available here for $21.95. There is no functional difference between these clones, if the cheaper one had been available when I was looking I would have bought it.