Not sure if this is a good place to ask this or not, but it's probably worth a try. I've got a Dell C1765NF colour laser printer, currently using non Dell toner cartridges. The printer had been working fine, until I send 3 separate A4 jobs to it.
The first one (which contained quite a lot of black) printed out fine, the next 2 the black came out smeary almost as though it were running out. I've checked the levels and it reports that the toner is 80% full.
Being non-Dell toners I thought there's a chance that maybe it's reporting being fuller than it is, so I popped in a new one and it didn't seem to make any difference. Here's a quick example of 4 colour dots working fine, and the black in the middle not looking right at all
A side note is that I noticed after trying to print that there was a noise coming from the black toner. There's a little cog that the printer can spin (no idea what it does) but I think it was spinning it for quite a while on the black.
Does anyone know what might be going on here and how to fix it?