Modern Vespa

Seat latch issue - it won't latch closed. On the rare time it does latch - absolutely no problem with it unlatching. Tried the shim trick and it didn't affect the issue.

Upon close inspection, when the button un-latches the seat, the hook part sticks out just a tiny amount from sitting flush. That tiny amount is enough for the latching bar part to push it down ahead of it, thereby closing the mechanism prematurely. If I use a screwdriver to push it back flush then it closes properly.

I've got a workaround where I pull the seat in the direction opposite the hook and it does okay. But won't that eventually torque the hinge on the other end of the seat? Is there something I could adjust to make the hook open that extra millimeter so that it is flush?

I did clean the mechanisim up and use some spray lithium grease on it, but it hasn't made any difference.

Old bike---try WD40

Loosen the bolts at the front of the seat, turn the seat a smidge, do up the bolts.

Or loosen the bolts holding the 'fixed' part of the latch and improve that part's positioning.

Either should work.

This happens on older Genuine Buddy and almost every Yamaha Zuma. I use lock dry lube (yes, that sounds crazy but it works) on the latch mech and do what Jimc said, concerning loosening the seat and/or latch base.

I use a bicycle chain lube made for dry, dusty conditions. It doesn't collect dirt or make a mess.