I think those will be hard to find.
I suggest getting a set of the current Lakland knobs. The pics on the website look VERY similar to the ones on your bass.
Either that, or do your own thing with a set of knobs.
Good luck on the quest!
ESP Ltd B-1005, ESP Ltd Surveyor-4 (incoming) Fender MP Jaguar, Squier VM Jazz V, Squier VM Fretless P, Squire Affinity Jazz V Fretless (in work) Mesa Walkabout Scout