Post your nozzle test
Post your cartridges from the left to the right
Look at the top of the head - You have four dampers - read me the colors going into the dampers
2nd bottom - etc
They won't but need to change the lines and dampers to prevent remnants of the old color. They will flush the lines and keep their fingers crossed.
Welcome, no need for new inks though - just correct lines from cartridge to damper - and if he only switched 1 and 8 (two circulating lines) then just dampers are required. All the best - that printer is a work horse.