Jerry:
On the 3710 that I had previously, the support legs had to be pinned or they would rotate, allowing the crossbar to contact the hood as you rolled back the bucket to lift the arms from the loader sockets that were attached to the tractor frame.
Actually, they were plenty beefy enough, with nice foot pads, just like the ones on my LA853. The difference is on the LA853, you must rotate the legs into an OFFSET hole and then pin them. Kubota also did away with the crossbar and the front mount so the loader essentially only mounts on 2 sockets.
There is absolutely no way to flex the side frames on the loader that was on my 3710 or on the 5030 for that matter.
One way you could sit the crossbar on the hood was by actually missing the sockets during a remount or by attempting to dismount the loader on extremely uneven ground. if the arms versus sockets aren't in the same plane, the arms could jump to the side of the sockets and drop the crossbar on the hood with a bang.
I think I stated in a thread to someone interested in a 5030, to dismount the loader on a LEVEL, preferably concrete or asphalt pad. It can be very tricky to remount if the loader is not on the same plane as the tractor. I know. I actually had to pin one side of the loader and drag it to a level spot and unpin it. Then I set the loader in both sockets. If I had had a crossbar loader, it would have dented the hood at that point.