After changing deveoper and drum printing output is too light and the density can't be adjusted

If you have replaced multiple components in your Brother 8510 printer, including the oven unit, laser unit, high voltage board, power board, and drum unit, but are still experiencing faded images, there are a few other potential causes and solutions to consider:
1. Toner Cartridge: Ensure that you are using a genuine and compatible toner cartridge for your Brother 8510. Low-quality or incompatible toner cartridges can result in poor print quality. Try replacing the toner cartridge with a new, genuine Brother cartridge to see if it resolves the issue.
2. Toner Density Settings: Check the toner density settings in the printer's software or control panel. If the density is set too low, it can result in faded or light printouts. Increase the toner density setting to see if it improves the print quality.
3. Cleaning the Corona Wire: The corona wire is responsible for transferring the toner to the paper. If it is dirty or contaminated, it can cause faded prints. Consult your printer's manual for instructions on how to clean the corona wire properly. Be careful when handling the corona wire as it is delicate.
4. Print Settings: Check the print settings on your computer or within the printer's software. Ensure that you are using the appropriate print quality settings and that any power-saving modes are disabled. Adjusting the print settings to a higher quality mode can enhance the print quality.
5. Contact Brother Support: If you have exhausted all the troubleshooting steps and the issue persists, it may be beneficial to reach out to Brother customer support or a qualified printer technician. They can provide further guidance or arrange for a professional inspection and repair of your printer.
Remember to follow the manufacturer's guidelines and safety precautions when working with printers and their components.

first did you clear the counter for the drum and developer before replacing them second did you run the required F 8 procedure if not need to buy new drum and developer. Start over the counters are cleared in service mode then you take the image unit out, then replace the drum and developer then re-install the image unit then run the the required F 8. ENSURE FAX LINE AND NETWORK cables are removed do not want a fax or print job to come in before running the f 8.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/normanj_7893313f0751935f

---Copy Density Sensor output adjustment-----
1. Sensor connector is disconnected.
2. Sensor is defective.
3. SPC PCB connector is disconnected.
4. SPC PCB is defective

there is a sensor in the drum unit that measures/sensors toner density on the drum. the sensor is usually dirty and needs a clean. there could be a number of causes so a technician needs to be called.

F2 02 Content Toner motor connector disconnected Detail Connection detection signal with toner motor is OFF Cause Connector harness defective Connector disconnected Check and remedy Check toner motor connector for connection. Check connector harness to main PWB for connection. Check harness for broken wire. F2 31 Content Process control trouble (OPC base surface reflection factor is improper) Detail Usually the sensor gain is adjusted so that the output is a certain value, by reading the drum base surface with the image density sensor before starting process control. However, a certain output is not obtained by adjusting the sensor gain. Cause Image density sensor defective Check and remedy Check process control sensor output with SIM44-03. (Do not adjust) If the result is far different from the specified value, it suggests the sensor is defective. Check the sensor and harness. If the deviation is relatively small, check the sensor and drum surface for contamination. F2 32 Content Process control trouble (drum marking sensor defective) Detail Usually the sensor gain is adjusted so that the output is a certain value, by reading the drum base surface with the drum marking sensor before starting process control. However, a certain output is not obtained by adjusting the sensor gain. Cause Drum marking sensor defective Improper connection of harness between PCU PWB and drum marking sensor Drum marking sensor contaminated OPC drum cleaning improper Charging voltage improper Check and remedy Check process control output with SIM44-02. (Do not adjust.) If the result is far different from the specified value, it suggests the sensor is defective. Check the sensor and harness. If the deviation is relatively small, check the sensor and drum surface for contamination. 9 –

F2 31 Content Process control trouble (OPC base surface reflection factor is improper) Detail Usually the sensor gain is adjusted so that the output is a certain value, by reading the drum base surface with the image density sensor before starting process control. However, a certain output is not obtained by adjusting the sensor gain. Cause Image density sensor defective Check and remedy Check process control sensor output with SIM44-03. (Do not adjust) If the result is far different from the specified value, it suggests the sensor is defective. Check the sensor and harness. If the deviation is relatively small, check the sensor and drum surface for contamination.

Content Process control trouble (OPC drum
surface reflection rate abnormality)
Detail Usually the sensor gain is adjusted so
that the output is a certain value, by
reading the drum base surface with the
image density sensor before starting
process control.
However, a certain output is not obtained
by adjusting the sensor gain.
Cause Image density sensor defective
Check Check process control sensor output with
SIM44-2. (Do not adjust)
and
remedy If the result is far different from the
specified value, it suggests the sensor is
defective. Check the sensor and harness.

If the deviation is relatively small, check
the sensor and drum surface for
contamination.

Content Process control trouble (OPC drum
surface reflection rate abnormality)
Detail Usually the sensor gain is adjusted so
that the output is a certain value, by
reading the drum base surface with the
image density sensor before starting
process control.
However, a certain output is not obtained
by adjusting the sensor gain.
Cause Image density sensor defective
Check Check process control sensor output with
SIM44-2. (Do not adjust)
and
remedy If the result is far different from the
specified value, it suggests the sensor is
defective. Check the sensor and harness.
If the deviation is relatively small, check
the sensor and drum surface for
contamination.

your laser printer
1) print color quality is now distorted that means print skew (technician called)
2) print tint means the print color not enough density,
3) print mottle means print dirty
you may try
1) print distorted--- find out the skew adjustment from your printer manu, it is adjust the image before transfer to the drum.
2) print skew could be happened when the drum replace install not very accurate, so install it more carefully.
3) print tint---you may increase print density from the manu, not fix,
4) print tint---the toner caridge near life cycle or using the less compatible toner. so you have change the quality toner or cartridge (if near life cycle) to improve quality photo print
5）print mottle---toner quality ? or cartridge near life cycle also cause print dirty paper,

try another drum unit.

i have the same problem