Hello, I'm helping a friend put a head gasket on his wife's 1997 Toyota Corolla 1.6L automatic. We removed the cam gear and failed to notice that there were two ways that it could go on. There are two slots on the gear that the pin on the cam could go into. One slot is marked with an "A", the other one with an "F". Can anyone tell me what the difference is & how we can be sure that we have it on correctly? Thanks in advance. Zeb