Oki B4100 - Manual (Page 273)

40055101TH Rev.4 273 /
Is the MCNT Board
mounted properly?
See ACTION 4.
Yes
Does the CHANGE
DRUM SOON message
remain on display?
No
Turn on power again.
No
See ACTION 3.
Mount it properly.
Yes
** CHANGE DRUM SOON **
Warning message to replace
ID unit because of its life.
Troubleshooting flow chart 2: