Here is a quick tip on fixing the streaking on the above printer
If you have streaking that is apparent on the prints and you don't suspect the toner cartridges or damage to the drum , chances are that the drum dust collector is full.
Drop front panel and remove all toners and also toner collector lhs pulls out.
Remove paper tray
pull out drum roller complete
As you rotate the drum roller by hand you will notice streaks being deposited on the drum. If you do not then you have another problem.
Remove two circlips from drum roller centre spindle
Carefully remove center pin and lift out drum taking care to not touch drum
Remove the bottom sponge roller by carefully pulling up and making sure you do not lose springs. Note direction installed by taking pix.
Now the very difficult part. Once you have removed roller you can see a slot which is probably full of old toner. DO NOT ATTEMPT TO BLOW OUT it will go EVERYWHERE and I mean everywhere. Get your OLD vacuum cleaner and take outside away from anything or anyone. Preferably outside in a field. Fire up the cleaner and as you gently tap the plastic case then hoover up the ensuing mess. This will trash your hoover filters as well so make sure you have a new set and a spare bag. Fit roller back in the right way round drive gear on right. Rotate the drum and carefully wipe the drum to remove any traces of streak. If its caked on you may have to scrap the drum and the printer. its a fiddle to get the spindle in so use a Phillips on the other end to help while pushing the roller. Toner is evil stuff so preferably wear a mask to ensure no particles are inhaled.
Might be worth emptying the toner collector while you are at it.
I will reiterate this again. Do NOT do this indoors or near any thing or one. Make sure the vacuum cleaner is running at all times to suck the toner up else it will deposit itself on your clothes and body, takes forever to get rid of.
I am not responsible in any way for this fix, it worked for me fine but its not for the faint hearted. The responsible way is probably to buy a new roller assy or throw the printer based on repair cost.
I have not tried this but you could also drop the assy into a large plastic bag and making sure the end is sealed tap the assy to remove the toner via the slot. Probably easier and does not affect your vacuum cleaner. I would still do it in a field though