Try a slightly smaller or softer Gel. I have a cyma and it used to be incredibly picky with ultra hard style gels. I used to have to run the ausgel pearl whites but have had alot of success recently with goats grown for 2 hours.
I was told once it was to do with the shape of the feed wheel in the magazine and the “scallops” not being deep enough.
Hope this helps.
The scallops not being deep enough makes perfect sense. I was a bit suspicious about that and thought that it could be a good job for the dremmel however tac edge have agreed to replace it under warranty, so the dremmel can stay in its box for now.
Thanks for the reply
Interestingly I had a mates blaster that was having a similar magazine issue, he had metal issue E&C Magazines, which looked strikingly like the Metal Cyma magazines, even though the magazine didn’t catch and stay seated in the well.
I grabbed one of my nylon Cyma mags and held it in place in his E&C and the blaster/mag fed and fire flawlessly.
Perhaps those metal E&C magazines are of the same design but with a different mag catch.
Anyone just adding some context in case someone has E&C Metal magazine issues in future 
I had the same issue with some of my mags, mainly from my Bohan Ar16. The gels seemed to clump up right before feeding into the wheel, since the part right before the wheel was large enough to fit 2 gels, instead of 1. I fixed it by putting a bit of thick gorilla tape on the ramp (leading under the wheel) right before the gels get pulled into the wheel. This lessened the amount of space where they were being fed. I’ll screenshot where I put the tape.
(I had to use more than one layer)