[Gaz64]

The rocker shaft broke from poor design in the first place.
Do they ever break in the middle?
No, because there is support of any rocker on both sides. The end rockers only have support on one side.

Once the shaft broke, the flexing of the shaft allowed the intake pushrod to dislodge and it gets bent up in the process.

Compression testing with no valve operation is not a fair test, since the cylinder is never exposed to atmospheric pressure during the intake stroke, a leakdown test would be more accurate.

The cylinder pressure is NOT the reason for the intake valve not opening, the shaft failure is.

Gary