Its very unlikely you have any problem! Don,t start making it a problem. I assume its in the airplane all you need to do is drip a little fuel in the glow plug hole and the carb then spin the engine a bit Like Da Rock suggested. As long as it spins free and feels smooth you do not need to remove the engine from the airplane and the back plate just to look. You might ask how do I know what is smooth? Well its a trainer right so we will let it train us. It feels smooth to you after you spun it a bit with some fuel then fine go fly if there are no other problems great you now know what feels smooth when feeling berings in an engine manually.

John