Considering what can go wrong without the correct tools I'd leave the seal alone if it looks still in place not moved at all. They're pretty robust seals, double lipped & sprung. That's just me taking the easy way out!! & wanting to make it easier for you. Of course I've been wrong before.

Thanks very much Automan!  Sorry for the delay.  Your response makes a lot of sense once I thought it through.  I used to think single cylinder 2-strokes were SO !