Brother HL 1230 - B/W Laser Printer Service Manual page 209

Note that each maintenance information is counted under the conditions below;
Information
Drum unit change
Toner cartridge change
Paper jam
Conditions
When drum unit life is 100 pages or more, and the drum counter is
reset. (Maximum counter: 63)
When the toner cartridge is replaced after a Toner Empty error is
stored in NVRAM, then warming-up completes without a Toner
Empty or Toner Low error being detected. (Maximum counter: 27)
When a paper jam occurs. (Maximum counter: 2047)
A-11
APPENDIX