Ok so your yellow dev is too low again. By changing dev you mean only replace the dev powder? Or did you change the dev tank? So in this case i will...
I also have a cheap code reader. For the most part, the data was not terribly useful to me. Like the error codes on the Canon iPF's, the errors often...
Go in service mode and check TCR levels. Then do toner add in service mode and recheck TCR settings. Should be higher normally.
Out of interest what...