Yes, all those 400k drives have an issue with grease hardening with time, the upper carrier should be removed (four screws) from the drive, the idea is to soften the accumulated grease and to help the carrier to move freely.
the most difficult part is a tiny lever at the lower end of the carrier, this is a locking lever responsible for leaving the carrier drop in the lower position, and making the disk get in touch with the reading head.
Be careful when removing the carrier, the head support is managed by a thin plastic arm, that can easily break under stress.tHANK