help with Two Ancient drives - broken pin and mysterious pin

[DracoJ]

Hello I've found these ancient IDE drives and I will try to read them via HDDSC.
But I also have 4 concerns, (see below)
(I wanna see what I can do first before sending to a Pro, files are probably not important anyway)

ST310211A v3.05
https://imgur.com/a/Up6HDRq

Product manual - ST310211A U8 Pin layout
https://imgur.com/a/fAuTY0d

1.) What's the broken Pin for? I checked the Seagate manual it's either "Hardware Reset" or "Ground" BUT Im still not sure, help.
2.) Is it safe for me to read the drive if that Pin is broken? How worse could it get if it isn't safe?
3.) Is it a non-essential Pin like... Ground?
4.) My other drive ST313021A v3.03 (see below) has a weird Shorter Pin compared to the rest.
I dont remember if this was cut or is it normally shorter by design, thoughts??

Other Drive: ST313021A v3.03
https://imgur.com/a/PAaZVyP

[fzabkar]

The missing pin is in the same row as the key. This makes it a ground pin. The drive should still work if this pin is missing.

The drive with the shorter pin has been damaged by inserting a keyed IDE cable upside down. Pin #20 is keyed, so it is this key which has pushed against the affected pin.

[DracoJ]

The drive with the shorter pin has been damaged by inserting a keyed IDE cable upside down. Pin #20 is keyed, so it is this key which has pushed against the affected pin.

So it's also still fine right? The shortened Pin #19 wont make the drive function bad?
I also recently found this diagram as a reference. https://imgur.com/a/UtTbDSa

[fzabkar]

Pin #21 (DMARQ) is the one that is pushed in.

[DracoJ]

Dang so that will make things more complicated if it isnt a ground?
Is it still safe for me to plug it?(assuming it can no longer reach the contact points of my adapter)?

[fzabkar]

Pull the pin out with pliers.