I've rarely called Dillon for replacement parts under warranty, but back when the powder measures were binding due to metal on metal fulcrum / powder bar wear they replaced everything I needed. I've read that they tightened up their replacement parts due to scammers re-selling them on Ebay.
Since then even though they used to have free replacement parts I stocked a goodly supply of replacements. The other day my primer feeder started flipping primers or not feeding at all, and it took 5 minutes to replace the plastic primer holder bottom of the primer tube. At least for the next several years or so I'm GTG
If you do not keep spare parts, having a spare parts kit on hand is surely better than waiting for parts to arrive by mail.