There is a throttle return spring, and there is a separate choke return spring. These springs are so similar, it is extremely difficult to tell them apart. Because of this, it is very common to have a choke spring where the throttle should be. The choke spring is slightly larger, so this will cause weak throttle return. If in doubt, we now have choke springs on hand.
There are two needed per car with HS2s.
If you are having choke issues, and would like some more info, check out our video about proper choke operation:
