Timing belt help

[walian at att.net]

Hello, I have a 97A6Q that I am in the process of
replacing the timing belt. I have put it on once and
then heard a rattle. It looks like one of the cam
sprockets was off 1 tooth.

when inserting the crankshaft hold down tool in the
crankshaft position sensor does the crankshaft have a
little divet? I am aligning the read mark on the ribbed
belt with the plastic holder behind its arrow. there is
a litte slack in the vibration dampener and want to
make sure I get it dead on.

how do you make sure that the teeth on the belt are
correct w/respect to the spocets. I used the alignment
tool when inserting the timing belts but the slack
moved and causing the mis alignment?

Can I screw up the engine if I am a tooth or so off?

Thanks

Frank