Thanks! I had bought a variety pack of some 70A durometer buna-nitrile o-rings, but as you mentioned the 90A are harder. It's not entirely clear to me the properties you'd want for this specific use, but given that it is used for friction to move the Snoo I think it makes some sense that you would want the harder ones.

Anyone that finds this in the future "202" is the size of the o-ring, it corresponds to the size 1/4" ID, 1/2" OD, 1/8" width.

I'm probably going to open my Snoo back up again this weekend to oil it to try to stop that squeak and inspect the silicone o-rings to see how they are looking.

I found 50 pack of the 202 90A o-rings for $6.57 on Amazon that I'm going to pick up just in case: https://www.amazon.com/dp/B0051XYYMQ - If you future reader try to buy these, just be careful that you don't make a change to the variation options (like pack size) that ends up changing the size that is selected.