Can anyone repair a Phaser 850 onsite?

did you switch the machine on and off

one of the paper sensors may be stuck pr damaged

The error is normally caused by the print head wiper being stuck to the print head or the print head pivot block being contaminated with spill over ink.
To clean the block you remove the left side cover. There is a stainless steel block about 1 inch by 1 inch about midway back on the lower frame. It would most likely have a lot of yellow ink in it.
If the wiper blade is tacked to the print head, you would remove the right and left cover. then remove the ink loader. ( where you place the ink sticks.). Once you remove the ink loader you are in the print head drum area and would gently detack the blade from the print head, then run the eliminate light stripes in the troubleshooting menu.

If I remember correctly, disconnect the print cable, then reboot the machine.
I saw that problem once and its been a while, but I do believe thats how I finally got it to stop.
Then clear out the print queue.

There is a wiper blade between the print head and the drum. Sounds like you have some buidup on it causing your problem.

I had a similar problem with another model. I went on line to the Co. and got all the info I needed.

I normally suggest running a long wood screw into the ink block to move it back and remove. If it's wedged then gently breaking it and removing or vacuuming the pieces out is your option.
The 07,010.43 code has nothing to do with the ink sticks. Although the result of removing the ink with the printer hot may have caused it.
That code is caused from the print head not moving from home position to the printing position. That print head pivots back and forth on a shaft.
One of 3 things has occured.
1. Ink has spilled into the stainless steel print head block. That block is located on the lower left side of the frame, looking from the front of the machine. The most frequent cause of that code is yellow ink seeping into that block from the machine eing moved while hot.
2. If the machine was unplugged before it was shut down. The Drum wiper assembly may be stuck to the print head, between the drum and print head.
3. One of the cables that run from the print head to the circiut boards that control it, may have shifted and are holding the print head back.
To remove the ink holder where those blocks are, requires removing the right and left side covers, that is held in by some plastic tabs, and 2 electrical connectors.

that code indicates most likely you have an ink stick in crooked, a broken ink stick in or added pieces of an ink stick.
That code is showing that you most likely have an ink stick loaded incorrectly or it broke.

Most likely a bad print heat. One of the ink heaters is overheating.

Yea I had the exact same problem with my Lexmark X1185
Was very lucky I didnt throw out the clear strip thingie before learning what it was :)

Anyways the strip itself passes through a shader sensor located on the rear or the cartridge carrier.( see pic 1 ) .





The second picture shows everything else in close detail Including which side of strip goes where.



Pay attention to the spring (circled in yellow) because i believe it is the cause of the whole problem...The spring end was pulled straight or has too little tension .

Not a problem, but turning it off causes the machine to do a setup, which then purges the ink supply and is very wastful.