How to recreate /dev/sr cdrom devices

I encountered a peculiar problem.
If multiple cdrom devices are mounted then /dev/sr1 is always skipped for unknown reasons.
It is as if it is blacklisted.

So how can I completely reset the /dev/sr1…/dev/srn n=0,1,2… devices and flush all system memory of /dev/srn so that /dev/sr1 can be used again. For some reason it is blocked from usedby the system without any device attached…

I tried the various options in the MAKEDEV manual, but nothing works.

Anyone know ho to do this ?