it's hard to tell, but the missing chip is going to be a regulator IC similar to the one next to the chip next to one of the missing caps. the difference will be what voltage comes out of the regulator. the missing cap next the regulator looks to be physically similar to the one next to the missing IC, so that might give you the value of the missing cap. the other cap, next to the smaller logic IC is going to be difficult because there doesn't appear to be another one like it on the board. so, now know you are missing a regulator IC similar to the one in the foreground that has a missing cap, but you don't know whether the output voltage is the same or different from the regulator chip in the foreground. you know the missing cap next to the regulator in the foreground is probably the same value as the one next to the missing regulator IC. the other cap next to the smaller logic IC looks similar to the four caps next to the right end of the barcode label, so measuring those might get you in the ballpark. since you have parts missing, it's really important to know how they became missing.... did they break off the board? were they desoldered? are all the PC board traces that go to the missing parts intact? something to seriously think about here, is is this drive actually worth it? when you can buy 2TB drives for $30, is it worth tinkering with a 1/2TB drive?... unless you're doing it for the sake of tinkering (which can be a lot of fun...). i have a couple of old RF signal generators, an old EICO vacuum tube type, and an old Knight JFET sig gen. i also have a HackRF and a MFJ antenna analyzer, which are useful as signal generators, and a lot more useful as measurement tools. but i still tinker with the old crude sig gens because that's what i had when i was a kid...