Try changing the last part to the following:
dBodyDisable(ode\body) if ch=1 then dBodySetPosition(ode\body,obx,oby,obz) ; Set linear velocity and rotational velocity to zero dBodySetLinearVel (ode\body, 0,0,0) dBodySetAngularVel (ode\body, 0,0,0) end if PositionEntity ode\mesh,obx,oby,obz dBodyEnable(ode\body) Next