>>+ was this a later version of feeder? Are the holes in the front part of an alternative or custom fixing method?
The Qplacers I just got use the side-lock thing. They're push (the feeder into the machine) to lock, push to unlock (except that one machine has a feeder irretrievably jammed in!)
There's an insert that goes into the hole you have there, looks kind of like a Dzus fastener.