Noob alert.. Headset bearings Q

Hi all, long time lurker. The first of many questions no doubt. I bought my first road bike, a Colnago ACR, last year, I've been really disappointed in general but that's another story. I'm suffering a clicking sound and have found it to be the headset bearings. I've taken them out and they are both really rough to spin, not good for a low mileage 15 month old bike. Anyhow, the bottom one is marked as 45° X 45° 970 1 - 1/4 an FSA one I believe and a quick Google easily finds a replacement. The top one however, has no markings and is a smaller variant with different dimensions. So finally, my question, in two parts - how would I determine what it is I require for the top and what would be an upgrade to the original as they don't seem to be very good. Many thanks, Sean.

Edit: I did find a replacement on a website specifically for the ACR but it states different measurements 1.1/8. To further add to my confusion.