Hi, First, I'm definitely an amateur at this. I have a little experience with Solid Works and F360. Since both have changed their license terms recently, and Alibre offered a nice deal to upgrade as I was a purchaser (Design Expert) a long time ago, I'm trying to convert my brain back to Alibre. I went through the basic design and assembly tutorial for the Crank/Pulley with an universal joint. I almost had the assembly working but there were some clearance issues which I modified some of the part lengths. When I place the crank/pulley/universal assembly in the base per the tutorial, it will not rotate. If I suppress the concentric constraint on either of the shafts and the base I am able to move the crank/pulley/universal assembly. Thanks for helping the neophyte.