My father in law's JD 420 lost a screw holding the air cleaner housing to the carb. It got sucked into the intake & lodged under the intake valve. I took my JD 430 to him today, then brought his 420 to my place so he could mow while I got his tractor fixed. His air cleaner housing was also all busted up where it bolts to the carb, so I have a good used housing to replace it. The valve & seat suffered no damage at all from the screw under the valve, as my FIL shut her down as soon as it stopped hitting on that side.