Thanks a bunch! I purchased Find #50, Locking Knob for Honing Wheel (part 7041) and Find #68, EzyLock for MSK-250 Shaft from Advanced Machinery (https://advanced-machinery.myshopify.com). Parts shipped quickly and now installed on my T4. Thanks for all the advice! I did not know, but Advanced Machinery is an authorized dealer for all Tormek parts in the U.S..