Bob,
The Willys came to me with no heat riser and the flapper seized. The only thing that was present was the spring and the disc. (Probably because they were rusted solid to the flapper pivot arm.) .
I bought the heat riser complete from a guy on ebay that claimed it was a take off. �Its was very rusty and old looking. �Came with the weight, disc, spring, screw, nut and the small odd shaped washer that locks the weight to the slot in the flapper shaft. �
Once I freed up the flapper, I installed the riser system and applied heat. (short blast of propane torch) �
The spring tightened up and raised the riser. Figured I was good to go. � I do have my old spring. (Someone here convinced me to never throw away old Willys parts.) �I could try the old one and see if it works better.