Xerox 4250 machine making squeaking noise - Xerox WorkCentre 4150 Black and White Copier

Try a different cartridge. While line typically means that no toner is being applied to the drum in that location. Would also explain the squeaks.

This could be a developer tank problem. What colour does the white line show up in?
Investigate that colour.
Good Luck.

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I have a Xerox 4250. After the ink cartridge ran out I replaced it with a new one and got the "replace photoreceptor cartridge" message. Reinserted the cartridge and it stayed. Called Xerox and they couldn't explain. I turned the machine off and on and the message changed to "replace photoreceptor cartridge" but an additional message of replace Smart Drum came up. I replaced the Smart Drum and it is working fine now. Note: I really don't think it was time to replace the Smart Drum. But the nearest authorized service provider was 3.5 hours away and this had to be cheaper than a service call from that distance.

The image unit 108R00591 is known to squeak.

You can also isolate the motors in diags. (Power-on the machine holding the back arrow and the "i" button and scroll to Motors) If any of them squeak then you have another suspect.

One of two things. The fuser bearings get noisy in those.
Or there are several small hard plastic rollers on steel shafts or even mounted on springs they they can get very noisy.

My Designer 1 started squeaking recently and, like you, I was concerned even though it sewed like usual. I emailed my tech. and he suggested either feed lifter mechanism or feed cam were the most likely causes - simple to repair but I would need to bring machine in for him to hear because there could be other reasons for the squeak. Well I did not have time to go then and there. Next day when I sewed, the squeak was gone!
At the time it squeaked I was sewing through several fairly thick layers (making a pot holder) and sewing very slowly. The next day I sewed normal cloth at normal speed but no matter how slowly I sewed, I could not get it to squeak. I will get it checked eventually but as long as it is squeak-less I'm not going to be concerned.
If yours squeaks all the time no matter what you are sewing then, yes, I think you should get it looked at. Be sure that nothing is rubbing against the body of the machine i.e. accessory tray and making the noise.

Look here, they have the manual for download.

THE BRAKE IS VERY FAMOUS FOR THAT NOISE NOT INSPECT THE PUMP ,, CAN BE GRINDING ON BOTTOM BASE OF WASHER ,, BEARING POPPED OUT