You don't need another alarm on the press ( and i'm not sure it would be possible -- without significant changes in press.../ i Reload at least 20,000 handgun rds a year on a 650 and I have never seen an issue like this on my press....and none of my buddies using 650's are having this issue....??
But the solution lies in the details...maybe you broke something in the primer feed mechanism....when did you last take it off the press and clean it out ( take it apart )....check all springs - in lever on top & one Under detent ball inside....make sure bolts are tight on top, make sure the priming seater is tight....is primer feed tube securely seated in mecanism with the knurled nut on top of tube holding it down....is shell plate tight.....make sure bolt holding the primer feed plate is tight.....all the little stuff...
But you should be able to easily feel when no primer is seated....
Remove it, take it apart, inspect, clean ....reinstall and check it again before continuing...
What caliber ?
What brand and kind of primers ?
How many rounds have you loaded on this press ?
( if it's. 45acp...are you sure cases are all using large pistol primers .... there are some cases out there using small pistol primers....)....
What did you mean, you have a .45 case on top....?? ...on top of what ?