How long since it has been apart? If someone had it apart recently, they may not have gotten that shaft tight in the hole. like I said, that pin is a taper fit and you actually drive it in the hole with a hammer to tighten it up.
If its been years since it was apart corrosion or vibration may have caused it to open up somewhat. Keep in mind that all those engines are over 20 years old at least. Probably more like 30 or 40.