Trying to repair a broken lock that does not turn at all by swapping the keying over to a new barrel.

Have extracted the circlip and removed the bits from the end. I was hoping when I removed these the inner barrel would simply slide out, and I would be able to swap over the bits from the old lock.

The only thing I can identify that I think there's a chance could be removed I have arrowed below, but it's not clear how it would come out if it does. There is a hole on the reverse side but with the components inside it it's not possible to pass something through to try knock it out. Any advice how to proceed would be much appreciated

Have you got the key in the barrel when trying to remove it from the outer casing? as the tumblers need to be in the 'unlocked' positiopn to get it out, I believe that once you have removed the circlip etc from the rear of the lock the barrel should just slide out (with the key in).

Yep, you need to put the key in the barrel to remove it.

Have tried with two different locks, and both the keys I have, and unfortunately it doesn't seem to help.