Loose Pitman Arm

[ursus]

I have a reballed Pitman arm that I bought from a vendor at a swap meet (remember those?) several years ago. When I began to install it I found that it is too loose even after cranking down hard on the clamp bolt. On one of the sector shaft flats I can insert a 0.008 inch feeler guage!

What is the best fix for this problem: shims, heat treatment followed by clamping the arm in a vice, or ...?