c284e Print Quality Issue

Hi all, I'm new to servicing copiers, not printers in general however...
just scored a cheap KM Bizhub c284e, that has done 335k. It printed ok generally, but with a smeary line always in the same place. Researching the problem I came to the conclusion that the transfer belt needed replacing, as the unit also said this was due. So I found one with blade at alixpress (none locally), and have just followed the video tutorials to replace it.
I don't know whether I have done something wrong, or what the issue is, but there is inconsistent print with lines on one end of the A3, and smudges, as highlighted in attached image.

 

The marks you're seeing are most likely from the drums, especially since that smaller mark you circled is repeating. If you print a full 11x17 page of 100% magenta, another with 100% yellow, one with 100% cyan, and one with black (try 100% and 50%, you'll be able to see which drum(s) is making the marks.