Original 1940s–50s O'Keefe & Merritt knobs are rare-find restoration parts ($30–$139 when available). Measure your Robertshaw stem and print a matched replacement.
OEM O'Keefe & Merritt knobs are often $25–$100 each — when they're still made. Design a replacement
with the exact bore for your shaft, in any color, printed in durable PETG and shipped for about $20.
Don't see your part number? Pull the broken knob off, check the
shaft (D-shafts: measure the diameter and the flat), and design yours — the bore presets cover
6mm, 8mm and 9mm D-shafts.