My YN-467 is acting very strangely. When the flash head is tilted at 75 degrees and 60 degrees, the flash will not fire at all, but in any other position it fires every time. I've tried recharging the batteries, changing modes, and turning it off and on - nothing seems to work. I'm just pressing the pilot button, not even trying to trigger the flash with something else. It seems like there must be something physically wrong with the connection at 60 and 75 degrees, but that seems strange because it works perfectly at 90 and 45 degrees. Has anyone else had a similar problem? Or any ideas for a solution?