I did my 1000 hour on my F70 Yamaha Monday and Tuesday. There was no
real drama, just a lot of "check/replace". I threw a water pump kit at
it and I was surprised that the kit comes with the shaft seals. It
turned out I needed them because here was trace water in the foot and
a drop of oil coming out of the intake screen. I also noticed Yamaha
has a better way because the bearing surface on the shaft seems to be
replaceable and the design seems to avoid getting sand on the seal (a
Merc problem on the "big foot") I ended up putting a "speedie sleeve"
in my Merc 60 BF because the shaft was scored.
I also threw a set of plugs at it but I am not sure why. They looked
brand new.

http://gfretwell.com/ftp/1078%20hour%20plug%20F70.jpg