I feel really silly now. I saw what I thought was a PEM threaded insert. Didn't realize it was just a pin.
Thanks for the tip on the lock. Will do what you suggested.
So with only 550lbs being able to release the tool holder, that would mean my holding force is too low!
I used the A-7Q-9-32050 from SDP-SI which are rated at 340 lbs compressed. I just realized my mistake between series and parallel arrangement. I will try them in parallel.
Do you know how much force the stock bearings can handle?