Since you stated that the old drive is showing signs of failure and you are trying to clone it to the new SSD, it is possible the process is not completing because there are unreadable sectors on the old drive. Have you tried to create an image of the old drive and then restore that image to the new drive?
My Dell 17" 7786 2 in 1 HD is starting to present some faliure and I want to upgrade to a larger SSD. I have 2x new Sandisk Ultra II SSD ( 1x 1TB and 1x500Gb) I would like to save everything right the way it is, recovery partition too... mantain support assist and all other dell stuffs that helps. So i boot my system with f12 and start "Support Assist OS recovery".. i choose to CLONE the entire SSD to the new SSD 1tTB using an external USB SSD DEVICE and i simply press - CONTINUE. So the process start and it goes with success for like 20 or 30 minutes. Since the external usb is 3.0 transfer speed is not so fast, but everytime i GET an "UNEXPECTED ERROR" and clone never complete. I have tried with the other Sandisk Utra 500Gb and got the same problem I've tried to use also macrium free SSD clone and also got a failure. I don't know how I will be able to clone this DELL 7786 HD to a new SSD
dell inspiron 7786 2-in-1 clone hd failure "UNEXPECTED ERROR"