I see several questionable things:
1) somebody has tanked and/or bead blasted all the plating off of the linkage. This makes me wonder if the green Teflon coating on the throttle shafts is gone, too.
2) You have double return springs on the throttle shaft linkage, which in and of itself isn't necessarily bad, but maybe the springs are too strong, and putting extra load on the "journal". Also, I suggest you anchor the end of the spring(s) on the throttle stud at the of the cable end shackle(between the "ears"), which lessens the constant torque on the linkage and throttle shaft journal.
I agree with comment about the glue sealing the constant feed well caps on the bottom of the bowl. The glue can be damaged by soaking in carb cleaner. You should never soak the bowls in carb cleaner. Just rinse them in a mild solvent, maybe scrub them a little with a soft toothbrush.
