Forum Thread: 7D Internal Flash Sync Problem

I recently got my 7D back after it was being fixed for a broken cf pin.

The problem now lies with the flash, the flash DOES pop and it does fire, but there's no flash effect on the photo sometimes. Heres 2 photos, same settings but 1 is iso 1600 and the second is iso 2000.

1) http://gyazo.com/9454f5ea945a1ecb9c3a919690361f1c

2) http://gyazo.com/68de03c4042a3826764e9e3aeca0b8bc

Both photos the flash did pop and did fire.