HP85a and hp9133H

[rprosperi]

It is very common that the floppy drives in these HP units have the sliding mechanisms inside (that both locks/ejects the diskette body and also lets the head move) stuck in-place as the grease/dust have dried and locked-up.

Open the case and remove the floppy unit and carefully clean the sliiding arms with alcohol. Though hard to describe, it's pretty easy to see once you handle the floppy drive unit, which arms are supposed to slide. After cleaning, lubricate the moving parts with a thin coat of light machine oil or silicone grease (sewing machine oil works fine and is easy to find).

Once cleaned and lubed, exercise the mechanisms by inserting and ejecting a diskette 10-20 times to 'work it in' before you put it back into the case. Also, make sure that the head is properly aligned and not previously damaged by someone that pulled a diskette out with the head still making contact (since the retract mechanism was stuck). If so, it MAY be possible to correct, but also may not, it depends on how damaged the head/retract arm is. If damaged, you will likely have to replace the floppy drive unit. If so, the Sony model number is usually listed on the drive and they are generally available on eBay or other vintage part sources, though you may have to be patient to find a cheap one.

Good luck.