I have a Xerox Phaser 8500n. My problem is on warmup it gives me a 07,10.43:34243 error code. can you give me a direction to look to try and fix this unit.

That is a common problem with that printer.
I will give you a rundown of what is the likely cause, about 99 percent sure of one of these things. What is happening is the print head is unable to pivot properly from the home position to print position.

1. The print head block is dirty, most likely problem. if you remove the left side cover, looking from the front of the machine.
About mid way back and toward the bottom of the frame, you will see a stainless steel block about 1 inch square. It has a spring assembly holding it in place. That block most likely is contaminated with some of the solid ink. You can just pull back and to the left to move the spring assemly out of the way and latch it to the frame. Then, you may need a pair of channel lock pliers to slip the block out and clean it and the print head shaft well. Soak the print block in some hot water to soften it a bit and make is easier to clean. Rememer it is HOT water.....
Then once those are clean, reassemble the printer.
2. The print head wiper assembly may be tacked to the print head between the print head and the drum. That will occur if the printer is not shut down properly or there was a power failure. You have to remove both the right and left hand covers, and the ink loader on top, the assembly where you load the sticks.It is just held in with a couple of tabs and 2 connectors. You will see the print head and drum once that is removes and look for the pink blade assembly tacked to the print head, gently remove it from the print head then run the procedures for removing light stripes and the one for removing smears.
3. The print head cables. They can move out of position and get caught on tabs in the printer. That would require removing the same items as if you were looking for a stuck blade. The 2 harnes and ribbon cables connect to the back of the print head, make sure they move freely and are not obstructed.
There is one other more obsecure problem with that, that is very unlikely you have, I have read it in a tip but never seen it.
One of those 3 things should resolve that code.