I do through all the entries for the disposal of non-current assets in my free lectures (we stopped calling them fixed assets many years ago).
If cash is not received because the asset was sold on credit, then we debit receivables instead of cash. If cash is not received because the asset was scrapped, then there is no entry for cash (but all the other entries remain the same). If cash is not received because the old asset was given in part-exchange for a new asset, then instead of debiting cash with the part-exchange value, we debit the new asset.
The lectures are a complete free course for Paper FA and cover everything needed to be able to pass the exam well.