Compounded problem: old Snapshots from Parallels 9 can't be deleted with v15 & 1 corrupt *.hdd*.hds

I'm in the midst of upgrading an old iMac Mid 2011. By now I upgraded to High Sierra. I bought an SSD disk and cloned it with an USB drive. I could not use Mac's clone function: there was a read error after which all stopped. I used ultracopier to do the Clone process. After about 15 hours, all was copied with 1 IO read error.

After some investigating I found out that a Windows 10 guest's *.pvm file was the problem. Which is weird, because the guest boots just fine on the old HDD. Disk Utilities' EHBO did not found any problems on the old HDD either (but SMART logs confirm the disk desperately needs replacement).

I then went to remove old Snapshots. I could delete a few recent ones, but Snapshots made with Parallels 9 (by me now upgraded to Parallels v15) cannot be deleted with the user interface.

After some Googling, I kinda figured out how the virtual machines work with Mac OS's parallels. SO I moved (copy file, delete file) 2 old Snapshots out of the Windows10.pvm (show archive contents) - Windows10-0.hdd - Windows10-0.hdd.0{STRING}.hds. Sure enough, a read error occured when I tried to copy the oldest .hds file out of the .pvm. Still, I continued and removed the 2 files, including the corrupt one. I tried to start the Windows10 guest-file from the old HDD. It wouldn't boot. So I made a copy of DiskDescriptor.xml (in Windows10-0.hdd) and did an edit, removing the blocks that referenced the 2 .hds files. Parallels still wouldn't boot (The hard disk image file used by the hard disk 6 (0) is corrupt and its data cannot be recovered).

So now I'm stuck - what to do?? I'll be moving the 2 .hds files back into the Windows10-0.pvm and restore the original DiskDescriptor.xml and hope at least the old HDD guest will boot again.

While I await confirmation of that: HELP - WHAT SHOULD I DO??

 

Correction: first line: bought an SSD disk and cloned it with an USB drive
Should read: bought an SSD disk and cloned the old HDD to the new SSD with an USB adapter to the SSD.

 

I restored the 2 files, though the oldest (corrupted) .hds file was a lot smaller after I copied it got back into the Windows10.hdd archive. Instead of about 65GB, all that remained was a 1.8GB file. Starting Windows 10 from the old HDD with this small .hds file still works. So I thought to replace the 2nd .hds file with a text file of the same name. That didn't work. Neither did replacing the 2nd .hds file with the corrupted small .hds file. That failed too though Windows would start and show a desktop. But programs wouldn't start etc. Putting the original 2nd .hds file back did work and Windows 10 would boot again (but I lost autologin - weird!). I'm now going to copy the Windows10.hdd file to my SSD. This will take a bit of time.

 

While I await the copy process and while strictly spoken, from an end-user perspective, I solved the problem, I'm not satisfied. Any way to;
1. get rid of the old .hds file that are irrelevant and big or messed up? Any manual file edits I could do and remove all irrelevant .hds files?
2. transfer the now somehow working Windows10.hdd to a fresh new parallels guest without all the irrelevant v9 Snapshots so I can shrink the .hdd file's size? Re-installing Windows 10 and starting from scratch isn't an option. I am working with an upgraded (licensed) Windows 7 to Windows 10 installation. It can only be installed once, so I'd have to start with Windows 7 again and upgrade all the way to 2020 :/

Thank you!

Devvie