cylinders gummy or sluggish?

Last weekend didn’t crank the flying wheel move about one inch at the time when I turn the ignition switch. I have two brand new 1000 crank marine batteries; I rebuild the starter, but same problem. Then I realized that is extremely hard to move the flying wheel by hand. I haven’t run that engine for only two month , but I have notice before that longer I don’t use it the hard it is to crank it, I use to blame the batteries charge, now I realized that engine get kind of stuck. Last night a remove the spark plug and put WD40 on the cylinder and loose it so much that I was able to move the flying wheel by hand, but the fallowing day it went back to the same stiffness. Don’t know to do…it could something on the gas that have the cylinders gummy or sluggish?
doming9@yahoo.com

[boats.net]

Need to remove cylinder heads to see whats happening, Cylinders may be rusty from water getting in.

Bearing

Could be the bearing at the bottom of the crank shaft or worn out cylenders take off the spark plugs and take a look inside with a boroscope if you cant see in a flash light. If every thing looks good then its most likly the bearing on the crank shaft.