DigiKey does not currently carry Prem Magnetics SPW-053 Transformer. A possible replacement would be Tamura MT1113-ND. Please review datasheet specifications to verify it will work for your exact application as there may be some differences.
Original SPW-053
Source - https://www.premmagnetics.com/content/SPW-050%20Series%20Data%20Sheet.pdf
Suggested Replacement MT1113-ND
Source - https://www.tamuracorp.com/clientuploads/pdfs/engineeringdocs/3FL20-125.pdf