g17 mag keeps falling apart

[nza]

with a fully loaded 10cap mag (not a 10/17) for my g17, once I insert the mag into the glock, and without chambering around, the baseplate falls off and the spring and all my rounds fall out.
I can't see exactly what is wrong, but I think i need a new baseplate. where to buy mag repair kits?

 

[Stevo]

Do you have the baseplate fully seated with the little lugs engaged?

 

[nza]

Mmm, I'll have to check, I have the mag as parts right now. I'll put it together and see how everything engages...
the mag, when full, in my pouch doesn't fall apart. its when I load, tap, rack, after the rack, it fails...

I wonder if either the lug isn't engagin the baseplate hole, or if the baseplate rail-hangers are too wide now...will check when I get home.