vertical streaks

[aposak]

I have a m375nw that has started printing vertical streaks on the pages, top to bottom. The first page of a multi-page print comes out clean or almost clean, the second with light streaking, and the rest with progressively worse streaking.... until the printer goes thru a cleaning cycle, and then the process starts all over with streaking about the same as the second page. The streaks appear to be black, but it could be all the colors printing together as well. My black is at 75%, and colors are all 90%. Could I have a bad toner cartridge? Does the printer need a good cleaning? And if so, how might I go about cleaning it? Thanks in advance.

[east2100]

It looks like you have a bad transfer belt needed to be replaced.

You can see it with toner tray pull out and take all four toner cartridge out where under the tray there's a black film like thing which it's the transfer belt. And you can see it with rear door open.

If you can see vertical streaks on the belt at the same side then it is.

It's useless trying to clean it just needed to be replaced.