Are you sure that is a D509 V2 ? The jumper layout is diff than others in the archives. can you take a picture of the label on the drive ?
What issues did you fix ? What computer/floppy controller is it connected too ?
I see it is jumped DS1, RD, MS, DC and LD.... which seems correct for some PC with setting as A: drive at end of twist or B: drive with no twist.

Checking some boxes here... Is it a High Density disk? Has it been formatted in another type of system previously? (Apple, Minix, VMS... ) Is the hub ring slipping due to poor clamping, worn or dirty spindle, worn disk?

Are the drive heads clean? , I had an issue with a 1.2mb floppy drive refusing to read disks because there was a layer of crud on the heads , took me forever to clean it off with qtips soaked in alcohol.
After that though it magically worked and has been fine ever since.

If it's hard to identify whether it's officially crud or not, remember it's 2 pantones lighter than cruft. 😉

BitWrangler wrote on 2022-10-12, 04:54:

If it's hard to identify whether it's officially crud or not, remember it's 2 pantones lighter than cruft. 😉

I dunno I'm not the greatest judge when it comes to gradations of grime 😆
I'll let the picture speak for itself.

I have the same problem/same error under DOS 6.22. Yesterday I installed a Panasonic ju-455-5 aag, this is a 360k diskdrive.
The only 5.25" disks I have to test are old C64/C128 disks with games. I guess that's my problem. It seems the drive cannot read C64 formatted disks. Would that be right?
I tried Fdformat, it will try to format the disk, but only when i turn of verification. Near the end, at cilinder 2, it goes wrong. Please advice!

C64 disks are usually Single Sided SSDD, to take a PC 360k format you need DSDD... now the slight catch is, if they were C64 and say DSDD on, were they actually good both sides DSDD originally, or was it a disk with a bad side, sold surplus to C64 market to use single sided.

BitWrangler wrote on 2022-10-12, 14:41:

C64 disks are usually Single Sided SSDD, to take a PC 360k format you need DSDD... now the slight catch is, if they were C64 and say DSDD on, were they actually good both sides DSDD originally, or was it a disk with a bad side, sold surplus to C64 market to use single sided.

Well, they where all DSDD and DSHD from several brands like 3M, Nashua, Verbatim.
100% filled with C64 games.
I tried several and they all acted the same when I tried formatting them as 360k.
I hope to get a few 'original' MS-DOS formatted floppies soon, so I can see if they will work.

Sometimes you just have to fire up a linux bootable CD or USB just to "dd" the disks so DOS doesn't go "There is information here I don't understand REEEEEEEE.."

Horun wrote on 2022-10-12, 01:36:

Are you sure that is a D509 V2 ? The jumper layout is diff than others in the archives. can you take a picture of the label on the drive ?
What issues did you fix ? What computer/floppy controller is it connected too ?
I see it is jumped DS1, RD, MS, DC and LD.... which seems correct for some PC with setting as A: drive at end of twist or B: drive with no twist.

Thank you comrade.
Yes I am sure for D509 V2. It is printed on the devices’ upper shield.
Yes I will. I already downloaded the manual which includes the jumper position for the usage.
I fixed some loose solder joints, a motor problem, I cleaned the device very well.
Two floppy are connected together, the other works fine, these two devices are on a controller on the same cable.
The A is the dead, and the B is a 3.5” 1.44Mb

Update from my side: Today I received two good MS-DOS formatted 5.25" disks. I placed them in my drive and voila, they worked fine!

Yesterday I tried to format the C64 disks using Linux, but that also gave errors. So, my guess is that C64/C128 formatted disks are not going to work this way. I will try Imagedisk and see what I can do with these C64 disks.
Maybe someone knows how to get these disks useable again on a MS-DOS machine.

Might be the normal 1.2Mb trying to write 360kb struggles, in that in low density mode, it only writes half a track, such that strong data flipped one way when it writes it the other, on the other half track keeps it from verifying. You kinda have to treat 360kb disks like CDRW.

Well, an update. I reveived 2 known good MS-DOS formatted disks. Reading them was no problem at all. Both disks checked to be 100% fine. Total of 360kb and no errors.
I tried to format one and it completed to 100% without an error. Then I looked at the summary it gave..... more then 600kb total space? Around 400kb not usable?
I tried formatting this disk again and guess what? Track 0 error and all the same issues as I have with these 'C64' disks.

Does this mean my drive is dead?

Formatting a 360K floppy disk in a 1.2MB drive is normally done with

format /f:360 a:
or
format /4 a:

Are you using that syntax ?

What is the drive configured as in the system's BIOS, presumably 1.2MB ?

Might be worth trying the problem drive alone one the floppy controller, possibly with a different cable, just in case .