I have a couple Sega trackballs, most are from Naomi panels so they're not too bad. The rollers have some wear but nothing significant enough to cause issues. I'm having problems with the optics on one (left and up are faster than right and down), and all my bearings are pretty sticky.
I've been trying to play Sonic and it's impossible if you don't have a perfectly smooth ball. I looked up bearing strats used by Golden Tee enthusiasts and it seems the general suggestion is to dissolve the factory grease in the bearings and replace it with oil (like Liquid Bearings or some sewing machine oil).
I skipped trying to clean them since they're double shielded and just tried letting liquid bearings seep in. It's definitely an improvement but still not perfect. I ordered some unshielded amazon bearings to clean and oil and they're so bad its worse than my old originals.