Does anyone have any advice on measuring cylinders with LKDMIS?

I have to measure automotive Stabilizer bars and am having limited success. The are no planes to generate vectors , no Cad, and the cylinders are "washed out" (not very straight). I have tried the measure/cylinder command, but I am required to know the vector of the cylinder. I have tried to measure individual points then construct the cylinder but it is very temperamental, and I get a "best fit" error.

I would appreciate any input.

Thanks,
Ian Price