I am sorry , how can I make search for this string in cloned copy post head transplant . I have not done so before and its not mentioned in ace manuals.
I tried to add these strings in grep search could not use it properly.
Hex view shows bTEC and sEDU eveywhere on cloned disk , but partition search in DE yields nothing ,neither any other softwares find any boot sectors.
I suspect this is the same case. Disk gives error while reading first sector & despite changing heads 8- 10 times this sector cannot get read.
There are some defective zones in the begining but later cloning is performed at 100mb/sec.
I want to at least isolate sEDU and bTEC affected sectors. Where can I get this information. We have raised ace tickets multiple times but they say it is not recoverable.

In DE -> Service - Grep Search. Add the references. Search. Once complete right click in results -> export to map. Service -> Fill with pattern -> sector was not read (or whatever you like).

Reread attempting to reduce misreads. Unless someone knows better ?

I don't think DE can do it on the fly as indicated MRT can though - it's not something that's come up here and none of it is listed in my version of DE of UDMA either.

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Data Recovery Services in the UK.
https://www.usbrecovery.co.uk/

Dear Team
Thank you for your help to solve this case. Unfortunately there is sad end to it.
I have taken back patient from customer and by changing heads multiple times have cloned it. I have identified bTEC sectors as well (sEDU were not found)
However all attempts to reread these sectors have failed .So even knowing exact technical issue why Bitlocker partition was missing ,I can't do anything practically. Total 18702 affected sectors (9.16MB) has been found.

Thank you all of you particularly DR-Kiev ,Lardman ,Michael chiklis ,vx1 to name a few.