There is no particular trick to replacing the impeller. Take out the 4 bolts
and one nut in the back (near that little stainless strainer) where the
cavitation plate meets the leg extension, drop the foot and you will see the
"can" where the impeller is. I seem to remember that these motors want you to
be in "forward" when you pull the foot and be sure it still is when you put it
back. If you don't mess with the linkage while you have it apart it should just
slide right back in. The only trick is getting the two splined shafts and the
water port all aligned. It is handy to have someoner helping so one person is
holding the foot and the other one is watching the shafts but I have done it
alone many times on my old 7.5 merc. Don't lose the rubber connector for the
water pipe or the washer that will fall out from under the nut.