Left flasher on F-150 1997

Hi there, i got problem when i put my left flasher on, i hear a fast clicling sound light like if a bulb is burn out, but sometimes my flasher flash anyway, i look all my left bulb and no one is burn out, do i should change it anyway, could be the light spring inside dont look burn but is slack a bit, i remark if i put left right left sometimes it works sound wierd for me, thanks in advance

Your multifuntion switch ( turn signal arm) is bad.