You're going to need to be more precise. I don't know who is fixing your drive but they need to be more accurate in what he/she reports to you so you can be more accurate in what you report here.
In response to Billdeg's message:
1) No, this is the same drive as the one I posted about a while back (I've spent a lot of time trying to fix this and getting nowhere)
I meant, drive 0 and drive 1 of the same 8050. Sometimes one drive will work fine and the other will not.
2) condition of caps are good and all the dodgy looking ones have been replaced. I don't know the rpm of the drives but all I know is that I tested the speed of them with a strobe light and they are fine.
Looks means nothing, you have to measure the caps ESR, but for now let's say we really don't know for sure if you have no actual measurements.
3) I remember using this command but with 'print'? It returns what you would except (can't remember), it was something like 75 commdodore DOS....
Gotta do this *exactly* after a fresh power-on cycle:
?ds$ [return]
The command: ?ds$ will tell you if the processor board of the disk drive is OK or not. The response you want will be something like: "73, cbm dos v. 2.x"
4) Command to format disk was 'header' (I think) and the directory is 'catalog'.
Before you use a disk you must format it. The command is:
header "disknamehere", d0, i01
(assuming you have a disk in drive 0 of an 8050 drive). NOTE: i01 assigns the identification name/number; 01” can be substituted for any two alpha characters. The system will respond "Are you sure? Y/N" or something like that before the format commences.
if you want to format a disk in drive 1 the command is
header "disknamehere", d1, i01
(if you re-format a disk, best to use a new value for i each time - i01, i02, i03, etc.)
"catalog" is not a CBM command. Just use the same two step commands you'd use for a c64 to run a directory:
load "$",8,0 (to see what's on the dist in drive 0, the right drive)
load "$",8,1 (to see what's on the dist in drive 1, the left drive)
follow the above command with LIST to see the directory.
Newer PETs have other directory commands (such as "DIRECTORY") available, but for sure you can use the above command on any PET except the oldest 2001's (with ROMS that pre-date the 2040 drive).
If the drive seems OK but will not locate (file not found) or run programs, try this:
open1,8,15,"I" (return)
...this command will help the drive head find its way back on track. That and cleaning the drive head itself with isopropyl alcohol is often the solution to a lazy drive.
5) At first the drive did give no error code. But now he tells me that it blinks 4 or 5 times which are unused error codes??
not good. You need to fix this first before you can do anything much.
4 flashes: there is no 8050 blink code of 4 flashes /unused
5 flashes: means that you have a controller ROM issue. See K3 and H3 on the 8050 board (check ROM/6530/6502)
If the drive light does not end in green you can't go much farther.