Progress bar reset and stuck during RAID drive image creation on Mac

I had a 12TB WD drive go wonky on me recently. It would show on Disk Utility but not mount. I tried some Terminal commands to force mount which failed. There are two partitions on my drive. One is about 12TB and the other is 150MB or so. I was able to mount the 150MB partition just fine using Terminal, but not the partition I need (with all my backup video projects). I had the bright idea of creating a disc image of the 12TB parition onto a RAID drive. It took about 26 hours but it made it successfully, but split the dmg files into parts. I tried to open the first dmg file and it didn't work, as I read should work. Great. So I read somewhere that I could try to piece the parts back together. I started to create a folder disk image of all the dmg parts. It was at about 90% done on the progress bar after a whole day so I left it clinking away overnight. I come back this morning and the progress bar is at maybe 5%. There is no cancel button and I'm afraid so screwing my new RAID drive up by force quitting Disk Utility. I don't mind if I screw up the image file I'm trying to create but I just got this RAID drive. Please help! Should I just wait to see if it finishes? Why did the progress bar go back down? Is the RAID drive I'm creating the disc image folder on in any danger of corruption if I force quit Disk Utility? Any insights would be greatly appreciated! Thank you * I checked Activity Monitor and it seems that Disk Utility is not doing much of anything. It did pop up to 0.1% CPU at one point. I also have something called com.apple.hiservices-xpcservice that's not responding. And the System percentage is red between 5-8%.