s200 loading bolt o-ring

[air gun]

my sons s200 had a bit of a pellet jam in the mag. cleaned the jam and saw the o-ring on the bolt was gone. we replaced the o-ring tonight and put the mag system back on the gun and found the gun strips the new o-ring when the gun is cocked. the bolt is really stiff. also before the pellet jam the gun was easy to cock. the bolt would pull back with no resistence. but now the bolt seems to have spring tention when the bolt is pulled back. its smooth and it must be cocking the hammer under spring tention. but it didn't do that before. crazy.