Thank you Gabi,
kindly understand the printer was printing well, all we did was replace the yellow toner and within minutes,
printer started showing different errors.
first error ws 061-319, then moved to 061-343.
as at this morning the errors have chaned and was initially showing 045-341 and now has moved to 061-341
Check first to see if the conductive pad under the black drum cartridge is present or not, like into the picture below
and to check the conditions of the drums like: