On rare occasions there have been problems with the single stage Primer Arms not tipping into the Turret presses.
On the Classic Turret Press (part number 90064), there are two raised pads that the Primer Arms should fall between. If the Arms are hitting one of the pads, turn the Shell Holder Adapter to position the Arms properly.
Another trick that has worked for some, is to attach a wire tie to the right front column. Position it so the extended tail of the tie hits the leg of the Primer Arm that is sticking out of the Ram. This will tip the Primer Arm into the Ram a little earlier in the stroke to avoid hitting the Shell Holder.