WD2500BEVT-75ZCT2 Replacement

The circle head in my Gateway T6836 appears to be missing the mark consistent with the WDC diagnostics utility. It passed the Quick Test but missed the mark the Extended test. It first declared it found unfavorable parts that would be able to be repaired but when it attempted to repair them it foundered and pointed me to WDC support.I ought to know depending on if I should displace it with the careful same model, or if there is a present model that can reinstate it with.In either case where would I be able to buy it?The more seasoned model is harder to spot and generally renovated, which I could want to escape.