I have been refurbishing an 18 x 36 Monarch lathe vintage unknown. It is overhead flat belt driven via a manual (looks to be original) transmission. Every thing works great but there is about 5 to 7 thousands run out on the threaded 2 1/4" x 8 spindle. The internal taper (# 12 Jarno) exhibits the same run out but the shoulder next to the bronze bearing journal is dead on. It appears that the outer threaded portion is bent. How can I repair this or work around it? I have no documentation.