I've had two drives doing this recently so I don't think it's the drives.

Can you access any of the files on the disks? I'm thinking you might be able to access what could be considered the first file on the disks?

I haven't fixed the issue but it happened with two drives and a bunch of old used disks so I assumed bad disks or bad drive config (cable, terminators, jumpers etc) and haven't had a chance to look at it since.

Iv been messing around with it since posting here, one of the disks not reading I was able to format and it appeared to work after that making test text files.

Another lets me run the data on the disk, but then wont let me xcopy data off the disk to make a backup.

What it seems like to me is the drive is having some error like its slipping, so small operations work, but when I try a big one that involves effecting the whole disks data like an xcopy it slips and gets an error.

The only think I can think of is that the lubrication could be dried out, but I cant find any guide to lubricating these drives.

Well, if you're not sure what you're doing then leave it alone until someone more knowledgeable comes along, you might knock the drives head our of alignment! 😀

Sometimes you gotta break things to fix them ;D But, Ill leave it till tomorrow to see if someone replies.

I dug up the maintenance manual for the drive and it says it does not require lubrication, but I don't think whoever wrote the manual was expecting it to be running 30 years later. All mechanical things need lubrication of some sort.

Hmm.. It's difficult to give a general advice in that case.
It could either be the floppy or the drive that causes the problem.

For example, if the drive was in use a long time ago (if it is not New Old Stock, NOS)
it could be the case that there's some dust on the magnetic head.
If that's the case, you can use some qtip and isoprop alcohol to gently clean the head.

However, it also could be the floppy disk..
Old floppies are sometimes slow going because of their fleece beeing worn or sticky.
A workaround - but not a fix - is to keep holding the lever of the 5.25" drive and
find the right "height" by trial and error. If the drive's head is slightly above the magnetic surface,
chances are good you can read some files. I used this "trick" several times to make backups of almost dead floppies.
It's not a fine method by any means, but it usually works long enough to make an image of a troublesome disk.
In case you want to try this yourself, use an imaging software with a retry function (winImage).

To me it looks more like a head misalignment or a sector misalignment than a dusty head because once he formated his floppy, it was functionnal. If you have another disk drive that is known to be working perfectly or if you know someone that has one, try the formated floppy on this disk drive. If it works without any issue then the floppy was previously formated with a faulty drive, if not then your drive has a problem with it's head position

Have you set 360 kB drive in the BIOS?

Do you use some special memory driver like UMBPCI that may cause DMA from the floppy controller to be unreliable?

Does the DD disk reads fine in another drive?

Thanks for the replies!

The only other 5.25 drive I have is on an Atrai 800.. so I don't think that will be helpful. The fact that different floppies, purchased from different sources both have the same issue suggests to me its the drive rather than the disks.
Also the disk are very nice Teflon ones they look brand new!

So I think Deksor may be right in saying the head misaligned. It may have been knocked in shipping.

Is there any guide to head realigning these drives anyone would recommend?

Could just be fading floppies. When they're just starting to show read errors, you can often still read them with enough retries. Some drives are better at reading weak floppies than others.

Or if they were all written with the same drive, it could've been a little out of alignment at the time, too.

Deksor wrote:

To me it looks more like a head misalignment or a sector misalignment than a dusty head because once he formated his floppy, it was functionnal. If you have another disk drive that is known to be working perfectly or if you know someone that has one, try the formated floppy on this disk drive. If it works without any issue then the floppy was previously formated with a faulty drive, if not then your drive has a problem with it's head position

Maybe, maybe not. Comparison is difficult whenever drives of different capacity are involved.
5.25" 360K and 5.25" 1.2MB, for example. If data is read/written one of them and then read/written on the other one of them,
then you can't be sure. There's a lot which can go wrong - different track spaceing, strength of the magnetic field, etc.
While misalingment of the drive's head is certainly possible, it is unlikely to happen I think.
Especially on a dumpy 5.25" drive which was almost never used. 😉

But I'm no floppy disk guru, so please let me quote something from this page.:

People compain they can't read 360K diskettes formatted or written on a 1.2M drive to be read on a 360K drive.
Briefly, the issue is that the 1.2M drive writes "thin" tracks, and also does not completely erase the "fat" tracks written on a 360K diskette.
Specifications for the track width and the erase width for 360K drives, and for 1.2M (also 720K) drives are at the head of this document.

Source:
Tech information on floppy disks drives and media
http://www.retrotechnology.com/herbs_stuff/drive.html

Good news! While researching floppy fixes I found a video about cleaning floppies with a qtip and some mentholated spirits.
https://www.youtube.com/watch?v=SCc9LNDwLmU

Allot of the disks I tested had a few spots on them, possible due to the damp climate here, anyway, cleaning those off seems to have allowed the disks to read normally.

I was able to make a few backups any any rate.