> I've hard a few hard drives fail in the past decades but I've always been able to retrieve the data

Care to share what kind of procedures you use?

I've recovered some data for friends and employers who want it back but aren't prepared to pay > USD1000 for it but if I cannot connect to the disk I'm lost.

(My tricks: tilting the disk, freezing the disk, leaving ssds powered on but sata unconnected, and even before that photorec and ddrescue etc.)

Note: don't do any of the above if data needs to be recovered at any cost, in that case just contact a data recovery company.