We just bought a red Garuda layer on E bay
It does not appear to have locking teeth and any combo we put together is loose and bursts easily. Did I get a fake or a dud? Or am I missing something?

No that's how it's supposed to be, on the right parts (Typically 7/4 Cross/Glaive Orbit/Atomic) it will be very hard to Burst despite the lack of teeth and looseness.