alpha 1 gen.2 won't drive prop in water

[EricVaughn]

I started my boat for the first time since winter and ran the boat with a motor flusher on the outdrive. I ran it for several minutes and then shifted the drive into forward, the prop spun smoothly. I took the boat to the boat launch and tried to back off the trailer the engine rpm's increased but the prop did not power the boat off the trailer. I did feel the gears engaging but not as pronounced as normal. When I winterized I may have ran the boat with out water for a minute or two accidentally due to the winterization kit. The engine may not have been properly winterized. Any insite will be appriciated.

regards.