Do you have a Delta kitchen faucet with loose handle? (Does the handle “wiggle”?) If you unscrew the handle, you’ll see that it sits on top of a cheap plastic nub. That plastic nub wears away over time. How did I fix he wiggle? I wrapped the plastic nub with a small piece of duct tape. That provided the right amount of material for a tighter fit.
UPDATE: This worked for about 6 months before I had to reapply more tape. Better than nothing!