Can some one help me. I have 2 motors for my 16' jon boat. One is a 1972 25 evinrude and the other is a 1965 9.5 evinrude. the 25 hasn't ran in about 2 years and the 9.5 has not been in the water for over 20 years. Both motors run great but I have spun both props on these motors. Is it because...