@coreyt @lewm has exactly the right idea. I had a close look at your turntable. The Michell arm and the RB3000 are VERY similar. I bet they both have the same spindle to pivot distance which is 222 mm. Making an arm board is child's play if you have the right tools. I assume an arm board came with the turntable? It would help to have one to use as a template. Also you need to check if you can get a blank arm board. Then, all you need to do is drill it. If you need help message me.