Thank you all for great suggestions! I tried them all. Sadly, the result is still to come.
I have a problem with CM4730 as well - it is an error 30.01.19 and blocked scanning/copy functions.
I got this device as a prank gift from collegues, without formatter.
I bought formatter from UK recyclers. Printing works fine. At startup, scanner does self-test, carriage moves and lamp lights couple times in one second intervals, but at the end of startup, system comes up with scanner initialisation failed 30.1.19 (which strangely is lamp error, but lamp lights up)
So far I tried to replace harddrive and upgrade firmware, but after upload, system reboots and after start, datecode is the same. Also, I have no access to any functions on fromt panel - just the error message, but I got the neccesary info from web. I see that a harddisk is recognised. I am also in a complete agreement with opinion, that it wouldn't be smart to start throwing parts at the device, considering that a Sandisk 2Gb CF card (with firmware) costs from 50 to 150$
I have repaired tens of 2430, 3005 4200 4350 and 5550 printers and I really like the simpliness and durability of them comparing to small SOHO printers. But this one is simply taking up space in my workroom and I cannot get it to work and I cannot get myself to rip it apart and sell by parts. Can anyone give me some more info?