Clear line to OM606 IP popping off

[okto]

So here's a fun problem. The plastic fuel line fitting (603 owners, I envy your banjo bolts) on the clear line to my IP keeps popping off.
The first time I put it back on, I noticed that the elaborately designed clip, which works something like a V-clamp for intake/exhaust fittings, was bent from the fitting being pushed out of the corresponding socket in the IP.
I bent the two arms that engage with the flange on the IP back into position, re-installed the fitting. No more than 200 miles later, it's already being pushed out and bending the clip again!
What gives? My fuel economy is in the toilet right now and I am not a happy dieseler!