If in doubt with a waterpump rebuild/replace.
Found some neat sites and some waterpumps for your engine. Here are the links.
http://www.oddjobmotors.com/scottatwater.htm
http://forums.iboats.com/Outboards/Scott-Atwater
http://www.iboats.com/Scott-Atwater-...view_id.268677
http://home.earthlink.net/~flyingscott/
http://discount-marine-parts.com/ob_scott_atwater.html
Have some pics of your engine?? Would love to see some!