Both my Airflows have original but damaged gear shift knobs. The collars are cracked and the threads are hogged out so they are loose on the shift lever. While I'm thinking up a way to restore them, I made temporary replacements out of 2-inch billiard balls by drilling them to 7 mm and tapping with M8x1.0 threads to fit the lever. I have some balls left and will be happy to send you one, drilled and tapped. Email me with your choice of the remaining balls, first come, first served. Sorry, 7 and 8 are gone as well as a couple others. You can PayPal me $8 for the USPS flat rate shipping cost in the US, and (this part is optional) if you want to subsidize my pawn shop drill press and brand new tap add another 10 bucks. You know, maybe I don't need to fix the originals. Just unscrew the billiard ball on Airflow National meet show day and drop the loose fitting originals on for judging!