Pull the valve cover and see what you find.

 

A locked motor could bow the starter to bits. lots of torque comes from it. Moving it 2 inches is not enough. get a breaker bar and turn the engine over without the sparkplugs in, and with the belt off. should be pretty easy with it in neutral. doing it with sparkplugs in and the belt on is going to be pretty hard. 2 inches will not tell you anything at all. Also by moving it by hand you will be able to hear if anything is out of the ordinary sound wise without all that extra engine noise.

 

the motor is NOT that hard to turn over...
you have been told to pull the plugs (look for wet plugs) and valvecovers (tug on springs to make sure valve stems are ok) and look...
just trying to get it to turn may not do anything but if something is in the way you dod not want to force it... but then again it may be too late...

Good luck and keep us posted...