Flash pictures too dark

[Skipper_81]

Hello,
I have a Panasonic Lumix which I have had for over a year. About a month ago my flash pictures started coming out too dark. I did not make any changes in the dials. The flash works -it just doesn't do the job.

 

[hang-the-9]

Flash bulbs burn out over time. Are they still lit up, just not as much as before?