B43 #19 has had similar issues but easily resolved by;
1.) adjusting latchhead to proper position then;
2.) tightening backing nut.
Have not had to do this with middle seat but there is a backing nut on latch. You have to be a contortionist to get to it on the B43. Into the port side locker, remove panel at rear of locker then squeeze through opening. o to back of boat with a flashlight.
My B43 #50 has had similar problems and it is laughable that the dealer would tell you that this is something that he/she is unaware of. I've had to crawl under the transom step into the gas locker area to make repairs to this item as well. These items regularly loosen up and fall off, usually into the locker or compartment. I am still to find my port side mechanism which fell deep into the locker a few months ago. I simply went and bought another.
On a side note, I also have problems with the interior push button latches for the cabinetry which seems to also break easily. Replacement parts are only $4 but I would hope Beneteau pays a little more for sturdier and higher quality in future builds.
Adjusting the striker plate will take the pressure off the latch mechanism and prevent failure.
We suffered from the same problem with our Euro built 43.
After correcting the adjustment with the backing nut a drop or two of Locktite on the threaded rod will prevent any further trouble.
Also where did Alan purchase replacement cabinet latches for only $4-00 each?.