Bearings failed I’d guess.
I’ve never had an o ring in my sha on the regency or any other bike and never had a problem.
My 14.12 sha on stock regency with a biturbo hacked on (hasn’t changed in over 10 years) is running a 56 Pacco jet (much to my surprise just now when I popped it open to check).
Anyone know if pacco jet sizing is...different? Because that seems v small. Haha