Failsafe vacuum canister diaphram

[gjz30075]

I recently had my headlights pop up and not go down with the engine running. They've always stayed down
for months. So I diagnosed it to be the vacuum canister. I swapped it for a spare I had and the system
now works a treat, as it should.

The canister I removed had no rust but felt 'sloppy' when actuating the rod so I decided to take it
apart. I don't see any rust inside the upper and lower 'cans' and I don't see any rips or tears in
the diaphram. Is it possible that the diaphram is so stretched out that the movement needed is
just not there? I plan to test the integrity of the diaphram in case I'm missing a rip somewhere.
Pictured is with the actuator fully extended. Should the diaphram be in this position?