Yes, recapitulating the toner is the work around. unless you happened to refill the capitulation control valve.
Hi, I cleaned everything, inserted type 28, made by sp mode initialization developer without toner. After I put in the toner bottle and photocopied. After 9 copies still sc390 error, the td sensor gives this data in sp mode 2.220 output td 0.00V / 2.49V.
Back to your original problem, might want to replace the TD sensor next. Oh, and since it appears to be bad that means the developer wasn't set properly, so you need another bag of developer. You should have just called a tech. Believe it or not, you have to be educated, trained and experienced to succeed in this specialized field of electromechanical machine repair. A youtube video on how to change developer does not mean you have any clue as to how the machine works, or how to fix it. Save yourself time and money, hire a pro.