Unless you have removed the engine, replaced motor mounts or bad motor mounts your engine should stay in alignment.
If the engine is out of alignment you would get symptoms like vibrations, because the drive shaft would no longer be in alignment with the PTO flywheel. I suppose that if the alignment was off a lot, the carbon ring would slip causing cavatation.
You need a special tool to align the engine, if you just need to check it you would be better off to take it to a dealer.
Lou