Need extention for wiindow crack to open window because of plantation blinds

We need an extension to the window crank. We had plantation blinds installed and the regular cranks will not turn because of the frame of the plantation blinds. We have tried several cranks available at the box stores and they have not worked. We ordered a crank from you we just sent back. It did not fit on the window crank. We need on extension or a crank that will fit on the window. The female fitting is 5/16" and the male end is 1/4".

Thank you!