Replaced airport card. Why is my wifi still spotty at best?

Hello

I've successfully managed to replace my iMac's aiport card (thanks to the ifixit-guide) but the connection is just as inconsistent as it was before. On rare occasions it works just fine but most of the time it'll be really slow. Sometimes it straight up doesn't connect.

I started experiencing these issues when I accidentally knocked the computer over and it fell on the floor a couple of years ago. The impact damaged both the internal hard-drive and, allegedly, the airport card. I decided to replace the internal hard-drive but not the airport card since it was no longer covered by warranty.

All these years later, I took it upon myself to finally replace the airport card, but it seems like it wasn't broken to begin with. But what else could it be?

I've grown quite fond of this machine so any advice will be appreciated.