The best way to check for bad seals. Change them. Belly up and put in the few dollars, and hours of work.
Of my now twelve Kawasaki sleds, nine of them had torn seals when I first got them. I do not even bother trying to start up a Kawasaki unless I just replaced the seals. My most memorable was a 530 motor guess why the person got rid of the motor. Same thing with the very newest 4/6 motor, the mag side seal was blown out.
I would take pictures of each seal blowout case, but then the redundancy would drive the forum crazy.