I have a colleague from the club who is 100% virgin reloader with a 750XL dillon press.
Ive been doing my best as a 650 owner to get him up to speed. Got some nice carbide dies and had her purring a fewbhundred rounds but now old mate is getting fail-to-primes.
Naturally any one of us would observe this instantly, but old mate managed to press a hundred without primers 
. Yes, everyone should be forced to start on a single stage. But its my fault for telling him to straight into progressive.
So, you guys with 750 prime systems, they are totally different to 650s. Any ideas why its not feeding?
Tube is aligned
Primers slide freely
Indicator says yes
Tip of primer tube is brand new abd aligned.
I don’t have an answer for you, but…
100% yes.
But I am an all-mighty internet expert, some of you know who I am talking about, lol, so I have 2 things to suggest. First, did he feed it primers; and did he tried turning it on and off again?
It seems the 750 is much easier to swap between small and large primers, doenst dump unused primers, at the expense of phantom mis primes.
The BrianPenis and Dillon forums are all still a bit rawn in their conclusions too.
The way I see it so far: alignment and tip condition and orientation being correct, adding weight to the feed rod to increase drop gravity really does help, but doesnt answer. I have a 45acp shell with a 230gn proj inserted as a weight. This treasts the symptom, but not the casuse.