Cleaning old AS/400 machine

Hi everyone,
We have two machines, old but but perfectly working : 9401-150 and
9402-400. We use it very often to when one of us has to test some COBOL
code without touching our production machine.
Because these two machines have been originally installed a lot of years
ago and now are full of various data, programs and configuration we would
like to remove.
In order to to that, we thought it would be better to perform a clean
install from CDs and clearing the disks to start over.
Because of our different moves these 15 or 20 last years, we are unable to
find the original CDs that were provided with.
IBM told me that the machine were not supported anymore so they are not
able to provide it. Our representative advised me to find CDs by myself and
that i should ask here. I asked several resellers but they can't understand
i need only the discs and not the licenses as our machines are already
licensed.
So if someone is able to retrieve old copies of the operating system
installation CDs, it would be very helpful for us. We need V4R5 and V4R4
(need to confirm exactly the installed versions).
Thank you very much in advance.
Best regards
Felix