First, the control board.
It controls every firing of the printhead and the precise ejection of every drop of ink. Many people try to save money by switching to unknown, off-brand boards, only to end up with the system throwing errors every few days. Print size misalignment is a minor issue — the worst-case scenario is unstable voltage instantly burning out your precision printhead, and that would be a huge loss. So remember: for the control board, either replace it with an original one or a compatible board that has been strictly certified by the manufacturer. Never go for cheap options.
Second, the UV lamp.
Don't think that as long as the UV lamp lights up, it will cure the ink — that's completely wrong. The key factors for a UV lamp are wavelength and power. If the wavelength is incorrect, the energy simply cannot be fully absorbed by the ink. If the power is insufficient, the surface of the ink may dry while the inside remains sticky, and it will peel off with a scratch. So when replacing the lamp, be sure to verify the original parameters of your machine. Don't let a single lamp ruin the adhesion of an entire print.
Third, the ink pump.
It is responsible for delivering ink steadily and evenly to the printhead. If you use a low-quality pump, the ink supply will fluctuate during operation — sometimes too much, sometimes too little. The printed pattern will have uneven color depth and unsightly banding. Even worse, it could cause the machine to run out of ink mid-print or scrap an entire batch of products. So the quality of the ink pump must be rock-solid — stable and durable. Replacing parts is not like fixing a bicycle. If you can't handle it yourself or are unsure, never force it. Consult the manufacturer or a professional.