After several of my PDs were damaged, I finally figured out the probable cause:

the system extension 'Apple CD-Rom' apparently is not aware of PD's and forces the drive to mark the cartridge as 'read-only'.  But as such, the drive can no longer mount it, unless it is in 'locked' position.
Such labeling cannot be overwritten by programs such as ' B's Crew'.
The only program I found to remove the Write-only label from PDs was Silverlining 5.81. After formating, the cartridge is cleared off its label and can be written again.

In addition, turned-on file sharing makes the cartridge very busy and sometimes seem to cause trouble.

Therefore I recommend:
remove Apple CD-ROM before inserting a PD-cartridge to the SCSI drive
turn off file sharing
test a normal CD first if the drive can mount it without problems

I haven't tested later operating systems because the later machines had nor SCSI-interface.