It has been well documented on these boards, that the plastic injector cartridges designed by Personna don't perfectly align with the Injector's head. This means it requires some fiddling to get the blade to inject correctly.
The actual metal Schick cartridges are said to be vastly superior. I found an actual Schick Injector cartridge at a small local pharmacy, and I plan on reloading it once it is empty (carefully of course, using a screwdriver to depress the spring, and a pair of pliers to actually insert the blade).
Agree - I have a stash of NOS blades in the metal cartridges - I think these are better than most of the blades currently on the market.
The only injector I've used was a G type eversharp-schick injector. It tore my face apart three times and I never touched it again.
GEMs give me close, easy shaves.
The older injectors (the ones with the small bakelite/plastic handles) are very aggressive shavers. The later models are much better shavers IMHO.