It probably has a dead spot on the armature if I am guessing right. So it will probably need replacement, otherwise, if you would describe stuck a bit more that would help.
Does it usually turn the engine over? Does it make a grinding noise? Does it spin without engaging the flywheel?
Stuck when hot could be vapor lock - when the starter is weak and can't turn the engine over against compression or pre-ignition.
So if you would, tell us more?
