I have an error message "Install MK" coming up on

SOURCE: Kyocera FS-9100DN

Go to the menu on the printer and then scroll down to other in the menu then to service then down to maintenance and press enter. when you install the maintenace kit you have to activate developer in the service menu, then turn off the printer and then back on to run the developer unit up.
Print menumap from the printer and follow through to the service area on the display.
Any question ask me.

SOURCE: Kyocera FS-4000DN, CALL SERVICE 6030:0159631

this error indicates a problem with the fuser unit.
if you are an end user, you will have to check warranty status with you nearest service agent and have the fuser replaced free or get a quotation if it is out of warranty

SOURCE: Kyocera FS-4000DN is showing install

> without buying a Maintenance Kit ?

Either you buy the kit, or you sell the printer "as is" on eBay, after buying a new printer.

SOURCE: kyocera FS-1016MFP "printer error service

Code: 6000
Contents: Broken heater lamp error
The temperature won't rise by 1°C/33.8
°F during warming up and the heater is
turned on for 5 seconds.
The temperature won't rise by 1°C/33.8
°F during printing and the heater is
turned on for 5 seconds with the duty
cycle more than 60%.

Causes:
- Defective fuser thermistor.
- Broken thermal cutout or heater lamp.
- Defective engine/high voltage PWB.