73 Swinger green turn signal arrow intermittent:

Noticed the last couple days the left hand side turn signal arrow (green in color) only lights up sometimes. I can hear the flasher turn on and off and the right hand side lights up fine. I can tap the cluster with my hand and it will come on and then go out after a few seconds.....I did just pull the cluster forward last week and swap the bulbs I could get to from behind.....any ideas?