Re: water impeller removal and installation
Remove the lower unit bolts & put the shift lever in drive. The foot will drop about 1", maybe 2". You'll see the shift rod & linkage. When you unbolt the linkage, have a friend catch the foot. Installation is the reverse, but make sure the linkage bolts & the brass coupling are in good shape, or you'll be doin this again. I had a stripped out coupling, so it would only shift when it felt like grabbin the bolt. Also, make sure the upper shaft is turned to the correct angle (like you took it off) or you'll have a re-assembly fight on your hands. Good luck!
BTW, The above is a great reference! I used that link to rebuild my powerhead, too!