XRAY - Model racing cars

Just wondering if anyone is having a problem with the front arms lasting recently?
I have just gone through a run of 5 front arms in only 2 meetings.

They all look like they have split along a seem on the under side of the inner hinge pin.
The original arms I had on the car didn't do this at all, but every arm since has gone in the exact same spot. Left and right arms in an identical spot.

It's starting to get a bit frustrating as I'm lucky to get an hours run time out of an arm yet the original arms lasted months
These arms have become harder and harder to get being out of stock at alot of shops for an extended period

I'm just about going through a left front arm every meeting. Mine are cracking at the front through the inside hinge pin. I've had no issues with right arms, only left. I've had none break yet, but thats due to replacing them before that happens.