Any ideas on how to replace a missing knob on a Steadicam Merlin (v1)?

which knob are you asking about?

I lost stuff from a merlin I had years ago. bhphotovideo had spares listed on their site.

Call steadtcam direct. I have lost several parts and they have sent them to me for free..no shipping. I suppose they are so used to fulfilling the needs their movie clients the Merlin is chump change. Anyway. the best parts department ever and you get to talk to a real person.